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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 del_avatar(self, a, b=None):
 """This is no longer my avatar, though it still exists on its own."""

        if self.engine._planning:
            raise NotImplementedError("Currently can't remove avatars within a plan")
        if b is None:
            if not isinstance(a, Node):
                raise TypeError(
                    "In single argument form, "
                    "del_avatar requires a Node object "
                    "(Thing or Place)."
                )
            g = a.character.name
            n = a.name
        else:
            g = a.name if isinstance(a, Character) else a
            n = b.name if isinstance(b, Node) else b
        self.engine._remember_avatarness(
            self.character.name, g, n, False
        )