results using previous task without creating new task

TaskManagingActor.swift

actor MyActor {
  var currentTask: Task<Void, Error>?

  @discardableResult
  func run<Value>(
    _ action: @Sendable (_ actor: isolated MyActor) async throws -> Value
  ) async rethrows -> Value {
    try await action(self)
  }
}

let myActor = MyActor()

try await myActor.run { myActor in
  if let currentTask = myActor.currentTask {
    return try await currentTask.value
  }

  let newTask = Task { /* some heavy task */ }
  myActor.currentTask = newTask
  defer { myActor.newTask = nil }
  return try await newTask.value
}