'Async version of incr().
Returns:
A UserRPC instance whose get_result() method returns the same
kind of value as incr() returns.'

def incr_async(self, key, delta=1, namespace=None, initial_value=None, rpc=None):

    return self._incrdecr_async(key, False, delta, namespace=namespace, initial_value=initial_value, rpc=rpc)
