'Run one of the idle callbacks.
Returns:
True if one was called, False if no idle callback was called.'

def run_idle(self):

    if ((not self.idlers) or (self.inactive >= len(self.idlers))):
        return False
    idler = self.idlers.popleft()
    (callback, args, kwds) = idler
    _logging_debug('idler:    %s', callback.__name__)
    res = callback(*args, **kwds)
    if (res is not None):
        if res:
            self.inactive = 0
        else:
            self.inactive += 1
        self.idlers.append(idler)
    else:
        _logging_debug('idler    %s    removed', callback.__name__)
    return True
