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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 file_name(self, file_type: Optional[FileType] = None) -> str: """Get a random file name with some extension. :param file_type: Enum object FileType :return: File name. :Example: legislative.txt """

        name = self.__text.word()
        ext = self.extension(file_type)

        return '{name}{ext}'.format(
            name=self.__sub(name),
            ext=ext,
        )