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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 is_ancestor(self, child_key_name, ancestor_key_name):
 """Returns True if ancestor lies in the ancestry tree of child."""


        # all keys are descendents of None
        if ancestor_key_name is None:
            return True

        one_up_parent = self.dct[child_key_name]['parent']
        if child_key_name == ancestor_key_name:
            # debatable semantics, but a person lies in his/her own
            # ancestry tree
            return True
        elif one_up_parent is None:
            return False
        else:
            return self.is_ancestor(one_up_parent, ancestor_key_name)