an instance of suspendable computation, i.e. the one that can suspend at some points and later resume execution possibly on another thread. Coroutines calling each other (and passing data back and forth) can form the machinery for cooperative multitasking. !10 Ҿ༻: https://github.com/Kotlin/KEEP/blob/master/proposals/coroutines.md 中断可能な計算インスタンス
aspects of function's behavior, thus allowing programmers to cooperate with Kotlin compiler by providing it with additional guarantees, getting more complete and intense analysis in return. !31 関数の振る舞いをコンパイラに伝える仕組み