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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 node_query(self, node):
 """ Return the query for the gql call node """


        if isinstance(node, ast.Call):
            assert node.args
            arg = node.args[0]
            if not isinstance(arg, ast.Str):
                return
        else:
            raise TypeError(type(node))

        return arg.s