def postinit(self, target=None, iter=None, ifs=None, is_async=None):
self.target = target<EOL>self.iter = iter<EOL>self.ifs = ifs<EOL>self.is_async = is_async<EOL>
Do some setup after initialisation.

        :param target: What is assigned to by the comprehension.
        :type target: NodeNG or None

        :param iter: What is iterated over by the comprehension.
        :type iter: NodeNG or None

        :param ifs: The contents of any if statements that filter
            the comprehension.
        :type ifs: list(NodeNG) or None

        :param is_async: Whether this is an asynchronous comprehension or not.
        :type: bool or None