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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 child(self, index):
 """ Returns the child associated with given index. Usage:: <AbstractCompositeNode object at 0x10107b6f0> u'MyNodeB' :param index: Child index. :type index: int :return: Child node. :rtype: AbstractNode or AbstractCompositeNode or Object """


        if not self.__children:
            return

        if index >= 0 and index < len(self.__children):
            return self.__children[index]