a first come, first served queing predicate for asyncio Condition

predicate.py

class my_turn:

    """a first come, first served coordinator predicate for
    asyncio.Condition.wait_for(predicate); could also do away
    the 'caller' by just hardcoding it to the current task
    """
    queue = []

    def __init__(self, caller):
        type(self).queue.insert(0, caller)

    def __call__(self, caller):
        if type(self).queue[-1] == caller:
            type(self).queue.pop()
            return True
        else:
            return False