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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 get_node_text(self, node):
 """ Return contatenated value of all text node children of this element """

        text_children = [n.nodeValue for n in self.get_node_children(node)
                         if n.nodeType == xml.dom.Node.TEXT_NODE]
        if text_children:
            return u''.join(text_children)
        else:
            return None