Get a new child :class:`Environment`.

        The child's scopes will be mine, with an additional empty innermost
        one.

        Returns:
            Environment: The child.

def new_child(self):
        """Get a new child :class:`Environment`.

        The child's scopes will be mine, with an additional empty innermost
        one.

        Returns:
            Environment: The child.
        """
        child = Environment(self.globals, self.max_things)
        child.scopes = self.scopes.new_child()
        child.things = WeakSet(self.things)
        return child