Simple coroutine like Python generator send()?

[tomyun]

I'm trying to learn Nim by translating existing Python code and one area I got 
stuck is to come up with simple coroutines. In Python, you can send back a 
value to the generator which can receive the value from yield statement. I 
found Nim has coro standard module for coroutines, but I'd be more interested 
in much simpler solutions to accomplish something like an example below. Any 
suggestions?
    
    
    def counter (maximum):
        i = 0
        while i < maximum:
            val = (yield i)
            # If value provided, change counter
            if val is not None:
                i = val
            else:
                i += 1
    
    >>> it = counter(10)
    >>> print it.next()
    0
    >>> print it.next()
    1
    >>> print it.send(8)
    8
    >>> print it.next()
    9
    >>> print it.next()
    Traceback (most recent call last):
      File ``t.py'', line 15, in ?
        print it.next()
    StopIteration
    
    
    Run

from 
[https://docs.python.org/2.5/whatsnew/pep-342.html](https://docs.python.org/2.5/whatsnew/pep-342.html)