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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def after(self, func=None, other_parents=None):
        '''Create a new Future whose completion depends on this one

        The new future will have a function that it calls once all its parents
        have completed, the return value of which will be its final value.
        There is a special case, however, in which the dependent future's
        callback returns a future or list of futures. In those cases, waiting
        on the dependent will also wait for all those futures, and the result
        (or list of results) of those future(s) will then be the final value.

        :param function func:
            The function to determine the value of the dependent future. It
            will take as many arguments as it has parents, and they will be the
            results of those futures.

        :param other_parents:
            A list of futures, all of which (along with this one) must be
            complete before the dependent's function runs.
        :type other_parents: list or None

        :returns:
            a :class:`Dependent`, which is a subclass of :class:`Future` and
            has all its capabilities.
        '''
        parents = [self]
        if other_parents is not None:
            parents += other_parents
        return after(parents, func)