Adds given child to the node.

        Usage::

            >>> node_a = AbstractCompositeNode("MyNodeA")
            >>> node_b = AbstractCompositeNode("MyNodeB")
            >>> node_a.add_child(node_b)
            True
            >>> node_a.children
            [<AbstractCompositeNode object at 0x10107afe0>]

        :param child: Child node.
        :type child: AbstractNode or AbstractCompositeNode or Object
        :return: Method success.
        :rtype: bool

def add_child(self, child):
        """
        Adds given child to the node.

        Usage::

            >>> node_a = AbstractCompositeNode("MyNodeA")
            >>> node_b = AbstractCompositeNode("MyNodeB")
            >>> node_a.add_child(node_b)
            True
            >>> node_a.children
            [<AbstractCompositeNode object at 0x10107afe0>]

        :param child: Child node.
        :type child: AbstractNode or AbstractCompositeNode or Object
        :return: Method success.
        :rtype: bool
        """

        self.__children.append(child)
        child.parent = self
        return True