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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 functions(self):
 """ Returns a generator of all standalone functions in the file, in textual order. 'the_first_function' 'not_auto_discovered' """

        def is_function(comment):
            return isinstance(comment, FunctionDoc) and not comment.member
        return self._filtered_iter(is_function)