Example of two equivalent programs as an illustration how you can transform coroutines into blocks. Pseudocode

1 coroutines.cpp

void main()
{
  int foo = rand();
  int result1 = await doSomethingAsync(foo);
  printf( "Result 1: %d", result1 );
  int result2 = await doSomethingAsync(foo + 1);
  printf( "Result 2: %d", result2 );
  return 0;
}

2 nocoroutines.cpp

void main()
{
  int foo = rand();
  void (^doSomethingAsyncCompletion2)(int) = ^( int result2 )
  {
    printf( "Result 2: %d", result2 );
  }
  void (^doSomethingAsyncCompletion)(int) = ^( int result1 )
  {
    printf( "Result 1: %d", result1 );
    doSomethingAsync(foo,doSomethingAsyncCompletion2);
  }
  doSomethingAsync(foo, doSomethingAsyncCompletion);
  return 0;
}