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suspend fun suspendingFunction(a: Int, vararg b: String)

request(arguments) { result ->
    runTask(result)
}

val result = request(arguments)
runTask(result)

fun suspendingFunction(a: Int, vararg b: String, $completion: Continuation<Unit>): Any?

suspend fun suspendingFunction(argument: String): Boolean {
    val result = mockRequest(argument)
    return result == 0
}

suspend fun mockRequest(argument: String): Int {
    delay(1000)
    return argument.length;
}

fun suspendingFunction(argument: String, completion: Continuation): Any? {

    val continuation: Continuation =
        if (completion is SuspendingFunctionStateMachine) completion.apply {
            if ((label or Int.MIN_VALUE) != 0) label -= Int.MIN_VALUE
        } else SuspendingFunctionStateMachine(completion)

    val result = continuation.result
    val resultTemp: Any? = null
    
    when (continuation.label) {
        0 -> run {
            throwOnFailure(result)
            continuation.argumentState = argument
            continuation.label = 1
            resultTemp = mockRequest(argument, continuation)
            if (resultTemp == COROUTINE_SUSPENDED) return COROUTINE_SUSPENDED
        }
        1 -> run {
            argument = continuation.argumentState
            throwOnFailure(result)
            resultTemp = result
        }
        else -> throw IllegalStateException("call to 'resume' before 'invoke' with coroutine")
    }

    return (resultTemp as Int) == 0
}

class SuspendingFunctionStateMachine(
    completion: Continuation
) : ContinuationImpl(completion) {

    var result: Any? = null
    var label: Int = 0
    var argumentState: Any? = null

    override fun invokeSuspend(result: Any): Any? {
        this.result = result
        this.label = (this.label or Int.MIN_VALUE)
        return suspendingFunction(null, this)
    }
}

fun suspendingFunction(argument: String, completion: Continuation): Any? {

    val continuation: Continuation =
        if (completion is SuspendingFunctionStateMachine) completion.apply {
            if ((label or Int.MIN_VALUE) != 0) label -= Int.MIN_VALUE
        } else SuspendingFunctionStateMachine(completion)

    // ..
}

class SuspendingFunctionStateMachine(
    completion: Continuation
) : ContinuationImpl(completion) {

    var result: Any? = null
    var label: Int = 0
    var argumentState: Any? = null

    override fun invokeSuspend(result: Any): Any? {
        this.result = result
        this.label = (this.label or Int.MIN_VALUE)
        return suspendingFunction(null, this)
    }
}

fun suspendingFunction(argument: String, completion: Continuation): Any? {

    // ..

    val result = continuation.result
    val resultTemp: Any? = null
    
    when (continuation.label) {
        0 -> run {
            throwOnFailure(result)
            continuation.argumentState = argument
            continuation.label = 1
            resultTemp = mockRequest(argument, continuation)
            if (resultTemp == COROUTINE_SUSPENDED) return COROUTINE_SUSPENDED
        }
        1 -> run {
            argument = continuation.argumentState
            throwOnFailure(result)
            resultTemp = result
        }
        else -> throw IllegalStateException("call to 'resume' before 'invoke' with coroutine")
    }

    return (resultTemp as Int) == 0
}

/**
 * Interface representing a continuation after a suspension point that returns a value of type `T`.
 */
@SinceKotlin("1.3")
public interface Continuation<in T> {
    /**
     * The context of the coroutine that corresponds to this continuation.
     */
    public val context: CoroutineContext

    /**
     * Resumes the execution of the corresponding coroutine passing a successful or failed [result] as the
     * return value of the last suspension point.
     */
    public fun resumeWith(result: Result<T>)
}

@SinceKotlin("1.3")
internal abstract class BaseContinuationImpl(
    // This is `public val` so that it is private on JVM and cannot be modified by untrusted code, yet
    // it has a public getter (since even untrusted code is allowed to inspect its call stack).
    public val completion: Continuation<Any?>?
) : Continuation<Any?>, CoroutineStackFrame, Serializable {
    // This implementation is final. This fact is used to unroll resumeWith recursion.
    public final override fun resumeWith(result: Result<Any?>) {
        // This loop unrolls recursion in current.resumeWith(param) to make saner and shorter stack traces on resume
        var current = this
        var param = result
        while (true) {
            // Invoke "resume" debug probe on every resumed continuation, so that a debugging library infrastructure
            // can precisely track what part of suspended callstack was already resumed
            probeCoroutineResumed(current)
            with(current) {
                val completion = completion!! // fail fast when trying to resume continuation without completion
                val outcome: Result<Any?> =
                    try {
                        val outcome = invokeSuspend(param)
                        if (outcome === COROUTINE_SUSPENDED) return
                        Result.success(outcome)
                    } catch (exception: Throwable) {
                        Result.failure(exception)
                    }
                releaseIntercepted() // this state machine instance is terminating
                if (completion is BaseContinuationImpl) {
                    // unrolling recursion via loop
                    current = completion
                    param = outcome
                } else {
                    // top-level completion reached -- invoke and return
                    completion.resumeWith(outcome)
                    return
                }
            }
        }
    }

    protected abstract fun invokeSuspend(result: Result<Any?>): Any?

    protected open fun releaseIntercepted() {
        // does nothing here, overridden in ContinuationImpl
    }

    // ..
}

@SinceKotlin("1.3")
// State machines for named suspend functions extend from this class
internal abstract class ContinuationImpl(
    completion: Continuation<Any?>?,
    private val _context: CoroutineContext?
) : BaseContinuationImpl(completion) {
    constructor(completion: Continuation<Any?>?) : this(completion, completion?.context)

    public override val context: CoroutineContext
        get() = _context!!

    @Transient
    private var intercepted: Continuation<Any?>? = null

    public fun intercepted(): Continuation<Any?> =
        intercepted
            ?: (context[ContinuationInterceptor]?.interceptContinuation(this) ?: this)
                .also { intercepted = it }

    protected override fun releaseIntercepted() {
        val intercepted = intercepted
        if (intercepted != null && intercepted !== this) {
            context[ContinuationInterceptor]!!.releaseInterceptedContinuation(intercepted)
        }
        this.intercepted = CompletedContinuation // just in case
    }
}

/**
 * Launches a new coroutine without blocking the current thread and returns a reference to the coroutine as a [Job].
 * The coroutine is cancelled when the resulting job is [cancelled][Job.cancel].
 *
 * The coroutine context is inherited from a [CoroutineScope]. Additional context elements can be specified with [context] argument.
 * If the context does not have any dispatcher nor any other [ContinuationInterceptor], then [Dispatchers.Default] is used.
 * The parent job is inherited from a [CoroutineScope] as well, but it can also be overridden
 * with a corresponding [context] element.
 *
 * By default, the coroutine is immediately scheduled for execution.
 * Other start options can be specified via `start` parameter. See [CoroutineStart] for details.
 * An optional [start] parameter can be set to [CoroutineStart.LAZY] to start coroutine _lazily_. In this case,
 * the coroutine [Job] is created in _new_ state. It can be explicitly started with [start][Job.start] function
 * and will be started implicitly on the first invocation of [join][Job.join].
 *
 * Uncaught exceptions in this coroutine cancel the parent job in the context by default
 * (unless [CoroutineExceptionHandler] is explicitly specified), which means that when `launch` is used with
 * the context of another coroutine, then any uncaught exception leads to the cancellation of the parent coroutine.
 *
 * See [newCoroutineContext] for a description of debugging facilities that are available for a newly created coroutine.
 *
 * @param context additional to [CoroutineScope.coroutineContext] context of the coroutine.
 * @param start coroutine start option. The default value is [CoroutineStart.DEFAULT].
 * @param block the coroutine code which will be invoked in the context of the provided scope.
 **/
public fun CoroutineScope.launch(
    context: CoroutineContext = EmptyCoroutineContext,
    start: CoroutineStart = CoroutineStart.DEFAULT,
    block: suspend CoroutineScope.() -> Unit
): Job {
    val newContext = newCoroutineContext(context)
    val coroutine = if (start.isLazy)
        LazyStandaloneCoroutine(newContext, block) else
        StandaloneCoroutine(newContext, active = true)
    coroutine.start(start, coroutine, block)
    return coroutine
}

private open class StandaloneCoroutine(
    parentContext: CoroutineContext,
    active: Boolean
) : AbstractCoroutine<Unit>(parentContext, active) {
    // ..
}

/**
 * Abstract base class for implementation of coroutines in coroutine builders.
 *
 * This class implements completion [Continuation], [Job], and [CoroutineScope] interfaces.
 * It stores the result of continuation in the state of the job.
 * This coroutine waits for children coroutines to finish before completing and
 * fails through an intermediate _failing_ state.
 *
 * The following methods are available for override:
 *
 * * [onStart] is invoked when the coroutine was created in non-active state and is being [started][Job.start].
 * * [onCancelling] is invoked as soon as the coroutine starts being cancelled for any reason (or completes).
 * * [onCompleted] is invoked when the coroutine completes with a value.
 * * [onCancelled] in invoked when the coroutine completes with an exception (cancelled).
 *
 * @param parentContext the context of the parent coroutine.
 * @param active when `true` (by default), the coroutine is created in the _active_ state, otherwise it is created in the _new_ state.
 *               See [Job] for details.
 *
 * @suppress **This an internal API and should not be used from general code.**
 */
@InternalCoroutinesApi
public abstract class AbstractCoroutine<in T>(
    /**
     * The context of the parent coroutine.
     */
    @JvmField
    protected val parentContext: CoroutineContext,
    active: Boolean = true
) : JobSupport(active), Job, Continuation<T>, CoroutineScope {

    // ..

    /**
     * Starts this coroutine with the given code [block] and [start] strategy.
     * This function shall be invoked at most once on this coroutine.
     *
     * First, this function initializes parent job from the `parentContext` of this coroutine that was passed to it
     * during construction. Second, it starts the coroutine based on [start] parameter:
     *
     * * [DEFAULT] uses [startCoroutineCancellable].
     * * [ATOMIC] uses [startCoroutine].
     * * [UNDISPATCHED] uses [startCoroutineUndispatched].
     * * [LAZY] does nothing.
     */
    public fun start(start: CoroutineStart, block: suspend () -> T) {
        initParentJob()
        start(block, this)
    }

    /**
     * Starts this coroutine with the given code [block] and [start] strategy.
     * This function shall be invoked at most once on this coroutine.
     *
     * First, this function initializes parent job from the `parentContext` of this coroutine that was passed to it
     * during construction. Second, it starts the coroutine based on [start] parameter:
     * 
     * * [DEFAULT] uses [startCoroutineCancellable].
     * * [ATOMIC] uses [startCoroutine].
     * * [UNDISPATCHED] uses [startCoroutineUndispatched].
     * * [LAZY] does nothing.
     */
    public fun <R> start(start: CoroutineStart, receiver: R, block: suspend R.() -> T) {
        initParentJob()
        start(block, receiver, this)
    }
}

/**
 * Defines start options for coroutines builders.
 * It is used in `start` parameter of [launch][CoroutineScope.launch], [async][CoroutineScope.async], and other coroutine builder functions.
 *
 * The summary of coroutine start options is:
 * * [DEFAULT] -- immediately schedules coroutine for execution according to its context;
 * * [LAZY] -- starts coroutine lazily, only when it is needed;
 * * [ATOMIC] -- atomically (in a non-cancellable way) schedules coroutine for execution according to its context;
 * * [UNDISPATCHED] -- immediately executes coroutine until its first suspension point _in the current thread_.
 */
public enum class CoroutineStart {
    
    // ..

    /**
     * Starts the corresponding block as a coroutine with this coroutine's start strategy.
     *
     * * [DEFAULT] uses [startCoroutineCancellable].
     * * [ATOMIC] uses [startCoroutine].
     * * [UNDISPATCHED] uses [startCoroutineUndispatched].
     * * [LAZY] does nothing.
     *
     * @suppress **This an internal API and should not be used from general code.**
     */
    @InternalCoroutinesApi
    public operator fun <T> invoke(block: suspend () -> T, completion: Continuation<T>) =
        when (this) {
            CoroutineStart.DEFAULT -> block.startCoroutineCancellable(completion)
            // ..
        }

    /**
     * Starts the corresponding block with receiver as a coroutine with this coroutine start strategy.
     *
     * * [DEFAULT] uses [startCoroutineCancellable].
     * * [ATOMIC] uses [startCoroutine].
     * * [UNDISPATCHED] uses [startCoroutineUndispatched].
     * * [LAZY] does nothing.
     *
     * @suppress **This an internal API and should not be used from general code.**
     */
    @InternalCoroutinesApi
    public operator fun <R, T> invoke(block: suspend R.() -> T, receiver: R, completion: Continuation<T>) =
        when (this) {
            CoroutineStart.DEFAULT -> block.startCoroutineCancellable(receiver, completion)
            // ..
        }

    /**
     * Returns `true` when [LAZY].
     *
     * @suppress **This an internal API and should not be used from general code.**
     */
    @InternalCoroutinesApi
    public val isLazy: Boolean get() = this === LAZY
}

/**
 * Use this function to start coroutine in a cancellable way, so that it can be cancelled
 * while waiting to be dispatched.
 */
internal fun <R, T> (suspend (R) -> T).startCoroutineCancellable(receiver: R, completion: Continuation<T>) =
    runSafely(completion) {
        createCoroutineUnintercepted(receiver, completion).intercepted().resumeCancellableWith(Result.success(Unit))
    }

/**
 * Creates unintercepted coroutine without receiver and with result type [T].
 * This function creates a new, fresh instance of suspendable computation every time it is invoked.
 *
 * To start executing the created coroutine, invoke `resume(Unit)` on the returned [Continuation] instance.
 * The [completion] continuation is invoked when coroutine completes with result or exception.
 *
 * This function returns unintercepted continuation.
 * Invocation of `resume(Unit)` starts coroutine immediately in the invoker's call stack without going through the
 * [ContinuationInterceptor] that might be present in the completion's [CoroutineContext].
 * It is the invoker's responsibility to ensure that a proper invocation context is established.
 * Note that [completion] of this function may get invoked in an arbitrary context.
 *
 * [Continuation.intercepted] can be used to acquire the intercepted continuation.
 * Invocation of `resume(Unit)` on intercepted continuation guarantees that execution of
 * both the coroutine and [completion] happens in the invocation context established by
 * [ContinuationInterceptor].
 *
 * Repeated invocation of any resume function on the resulting continuation corrupts the
 * state machine of the coroutine and may result in arbitrary behaviour or exception.
 */
@SinceKotlin("1.3")
public actual fun <R, T> (suspend R.() -> T).createCoroutineUnintercepted(
    receiver: R,
    completion: Continuation<T>
): Continuation<Unit> {
    val probeCompletion = probeCoroutineCreated(completion)
    return if (/* .. */)
        // ..
    else {
        createCoroutineFromSuspendFunction(probeCompletion) {
            (this as Function2<R, Continuation<T>, Any?>).invoke(receiver, it)
        }
    }
}

/**
 * This function is used when [createCoroutineUnintercepted] encounters suspending lambda that does not extend BaseContinuationImpl.
 *
 * It happens in two cases:
 *   1. Callable reference to suspending function,
 *   2. Suspending function reference implemented by Java code.
 *
 * We must wrap it into an instance that extends [BaseContinuationImpl], because that is an expectation of all coroutines machinery.
 * As an optimization we use lighter-weight [RestrictedContinuationImpl] base class (it has less fields) if the context is
 * [EmptyCoroutineContext], and a full-blown [ContinuationImpl] class otherwise.
 *
 * The instance of [BaseContinuationImpl] is passed to the [block] so that it can be passed to the corresponding invocation.
 */
@SinceKotlin("1.3")
private inline fun <T> createCoroutineFromSuspendFunction(
    completion: Continuation<T>,
    crossinline block: (Continuation<T>) -> Any?
): Continuation<Unit> {
    val context = completion.context
    // label == 0 when coroutine is not started yet (initially) or label == 1 when it was
    return if (context === EmptyCoroutineContext)
        object : RestrictedContinuationImpl(completion as Continuation<Any?>) {
            private var label = 0

            override fun invokeSuspend(result: Result<Any?>): Any? =
                when (label) {
                    0 -> {
                        label = 1
                        result.getOrThrow() // Rethrow exception if trying to start with exception (will be caught by BaseContinuationImpl.resumeWith
                        block(this) // run the block, may return or suspend
                    }
                    1 -> {
                        label = 2
                        result.getOrThrow() // this is the result if the block had suspended
                    }
                    else -> error("This coroutine had already completed")
                }
        }
    else
        object : ContinuationImpl(completion as Continuation<Any?>, context) {
            private var label = 0

            override fun invokeSuspend(result: Result<Any?>): Any? =
                when (label) {
                    0 -> {
                        label = 1
                        result.getOrThrow() // Rethrow exception if trying to start with exception (will be caught by BaseContinuationImpl.resumeWith
                        block(this) // run the block, may return or suspend
                    }
                    1 -> {
                        label = 2
                        result.getOrThrow() // this is the result if the block had suspended
                    }
                    else -> error("This coroutine had already completed")
                }
        }
}

/**
 * Persistent context for the coroutine. It is an indexed set of [Element] instances.
 * An indexed set is a mix between a set and a map.
 * Every element in this set has a unique [Key].
 */
@SinceKotlin("1.3")
public interface CoroutineContext {
    /**
     * Returns the element with the given [key] from this context or `null`.
     */
    public operator fun <E : Element> get(key: Key<E>): E?

    // ..

    /**
     * Key for the elements of [CoroutineContext]. [E] is a type of element with this key.
     */
    public interface Key<E : Element>

    /**
     * An element of the [CoroutineContext]. An element of the coroutine context is a singleton context by itself.
     */
    public interface Element : CoroutineContext {
        /**
         * A key of this coroutine context element.
         */
        public val key: Key<*>

        public override operator fun <E : Element> get(key: Key<E>): E? =
            @Suppress("UNCHECKED_CAST")
            if (this.key == key) this as E else null

        // ..
    }
}

/**
 * Marks coroutine context element that intercepts coroutine continuations.
 * The coroutines framework uses [ContinuationInterceptor.Key] to retrieve the interceptor and
 * intercepts all coroutine continuations with [interceptContinuation] invocations.
 *
 * [ContinuationInterceptor] behaves like a [polymorphic element][AbstractCoroutineContextKey], meaning that
 * its implementation delegates [get][CoroutineContext.Element.get] and [minusKey][CoroutineContext.Element.minusKey]
 * to [getPolymorphicElement] and [minusPolymorphicKey] respectively.
 * [ContinuationInterceptor] subtypes can be extracted from the coroutine context using either [ContinuationInterceptor.Key]
 * or subtype key if it extends [AbstractCoroutineContextKey].
 */
@SinceKotlin("1.3")
public interface ContinuationInterceptor : CoroutineContext.Element {
    /**
     * The key that defines *the* context interceptor.
     */
    companion object Key : CoroutineContext.Key<ContinuationInterceptor>

    public override operator fun <E : CoroutineContext.Element> get(key: CoroutineContext.Key<E>): E? {
        // ..
        @Suppress("UNCHECKED_CAST")
        return if (ContinuationInterceptor === key) this as E else null
    }

    // ..
}

/**
 * Marks coroutine context element that intercepts coroutine continuations.
 * The coroutines framework uses [ContinuationInterceptor.Key] to retrieve the interceptor and
 * intercepts all coroutine continuations with [interceptContinuation] invocations.
 *
 * [ContinuationInterceptor] behaves like a [polymorphic element][AbstractCoroutineContextKey], meaning that
 * its implementation delegates [get][CoroutineContext.Element.get] and [minusKey][CoroutineContext.Element.minusKey]
 * to [getPolymorphicElement] and [minusPolymorphicKey] respectively.
 * [ContinuationInterceptor] subtypes can be extracted from the coroutine context using either [ContinuationInterceptor.Key]
 * or subtype key if it extends [AbstractCoroutineContextKey].
 */
@SinceKotlin("1.3")
public interface ContinuationInterceptor : CoroutineContext.Element {

    // ..

    /**
     * Returns continuation that wraps the original [continuation], thus intercepting all resumptions.
     * This function is invoked by coroutines framework when needed and the resulting continuations are
     * cached internally per each instance of the original [continuation].
     *
     * This function may simply return original [continuation] if it does not want to intercept this particular continuation.
     *
     * When the original [continuation] completes, coroutine framework invokes [releaseInterceptedContinuation]
     * with the resulting continuation if it was intercepted, that is if `interceptContinuation` had previously
     * returned a different continuation instance.
     */
    public fun <T> interceptContinuation(continuation: Continuation<T>): Continuation<T>

    /**
     * Invoked for the continuation instance returned by [interceptContinuation] when the original
     * continuation completes and will not be used anymore. This function is invoked only if [interceptContinuation]
     * had returned a different continuation instance from the one it was invoked with.
     *
     * Default implementation does nothing.
     *
     * @param continuation Continuation instance returned by this interceptor's [interceptContinuation] invocation.
     */
    public fun releaseInterceptedContinuation(continuation: Continuation<*>) {
        /* do nothing by default */
    }

    // ..
}

/**
 * Base class to be extended by all coroutine dispatcher implementations.
 *
 * The following standard implementations are provided by `kotlinx.coroutines` as properties on
 * the [Dispatchers] object:
 *
 * * [Dispatchers.Default] — is used by all standard builders if no dispatcher or any other [ContinuationInterceptor]
 *   is specified in their context. It uses a common pool of shared background threads.
 *   This is an appropriate choice for compute-intensive coroutines that consume CPU resources.
 * * [Dispatchers.IO] — uses a shared pool of on-demand created threads and is designed for offloading of IO-intensive _blocking_
 *   operations (like file I/O and blocking socket I/O).
 * * [Dispatchers.Unconfined] — starts coroutine execution in the current call-frame until the first suspension,
 *   whereupon the coroutine builder function returns.
 *   The coroutine will later resume in whatever thread used by the
 *   corresponding suspending function, without confining it to any specific thread or pool.
 *   **The `Unconfined` dispatcher should not normally be used in code**.
 * * Private thread pools can be created with [newSingleThreadContext] and [newFixedThreadPoolContext].
 * * An arbitrary [Executor][java.util.concurrent.Executor] can be converted to a dispatcher with the [asCoroutineDispatcher] extension function.
 *
 * This class ensures that debugging facilities in [newCoroutineContext] function work properly.
 */
public abstract class CoroutineDispatcher :
    AbstractCoroutineContextElement(ContinuationInterceptor), ContinuationInterceptor {

    /** @suppress */
    @ExperimentalStdlibApi
    public companion object Key : AbstractCoroutineContextKey<ContinuationInterceptor, CoroutineDispatcher>(
        ContinuationInterceptor,
        { it as? CoroutineDispatcher })

    /**
     * Returns `true` if the execution of the coroutine should be performed with [dispatch] method.
     * The default behavior for most dispatchers is to return `true`.
     *
     * If this method returns `false`, the coroutine is resumed immediately in the current thread,
     * potentially forming an event-loop to prevent stack overflows.
     * The event loop is an advanced topic and its implications can be found in [Dispatchers.Unconfined] documentation.
     *
     * A dispatcher can override this method to provide a performance optimization and avoid paying a cost of an unnecessary dispatch.
     * E.g. [MainCoroutineDispatcher.immediate] checks whether we are already in the required UI thread in this method and avoids
     * an additional dispatch when it is not required.
     *
     * While this approach can be more efficient, it is not chosen by default to provide a consistent dispatching behaviour
     * so that users won't observe unexpected and non-consistent order of events by default.
     *
     * Coroutine builders like [launch][CoroutineScope.launch] and [async][CoroutineScope.async] accept an optional [CoroutineStart]
     * parameter that allows one to optionally choose the [undispatched][CoroutineStart.UNDISPATCHED] behavior to start coroutine immediately,
     * but to be resumed only in the provided dispatcher.
     *
     * This method should generally be exception-safe. An exception thrown from this method
     * may leave the coroutines that use this dispatcher in the inconsistent and hard to debug state.
     */
    public open fun isDispatchNeeded(context: CoroutineContext): Boolean = true

    /**
     * Dispatches execution of a runnable [block] onto another thread in the given [context].
     * This method should guarantee that the given [block] will be eventually invoked,
     * otherwise the system may reach a deadlock state and never leave it.
     * Cancellation mechanism is transparent for [CoroutineDispatcher] and is managed by [block] internals.
     *
     * This method should generally be exception-safe. An exception thrown from this method
     * may leave the coroutines that use this dispatcher in the inconsistent and hard to debug state.
     *
     * This method must not immediately call [block]. Doing so would result in [StackOverflowError]
     * when [yield] is repeatedly called from a loop. However, an implementation that returns `false` from
     * [isDispatchNeeded] can delegate this function to `dispatch` method of [Dispatchers.Unconfined], which is
     * integrated with [yield] to avoid this problem.
     */
    public abstract fun dispatch(context: CoroutineContext, block: Runnable)

    // ..

    /**
     * Returns a continuation that wraps the provided [continuation], thus intercepting all resumptions.
     *
     * This method should generally be exception-safe. An exception thrown from this method
     * may leave the coroutines that use this dispatcher in the inconsistent and hard to debug state.
     */
    public final override fun <T> interceptContinuation(continuation: Continuation<T>): Continuation<T> =
        DispatchedContinuation(this, continuation)

    @InternalCoroutinesApi
    public override fun releaseInterceptedContinuation(continuation: Continuation<*>) {
        (continuation as DispatchedContinuation<*>).reusableCancellableContinuation?.detachChild()
    }

    // ..
}

internal class DispatchedContinuation<in T>(
    @JvmField val dispatcher: CoroutineDispatcher,
    @JvmField val continuation: Continuation<T>
) : DispatchedTask<T>(MODE_ATOMIC_DEFAULT), CoroutineStackFrame, Continuation<T> by continuation {
    
    // ..

    override fun resumeWith(result: Result<T>) {
        val context = continuation.context
        val state = result.toState()
        if (dispatcher.isDispatchNeeded(context)) {
            _state = state
            resumeMode = MODE_ATOMIC_DEFAULT
            dispatcher.dispatch(context, this)
        } else {
            executeUnconfined(state, MODE_ATOMIC_DEFAULT) {
                withCoroutineContext(this.context, countOrElement) {
                    continuation.resumeWith(result)
                }
            }
        }
    }

    // ..
}