Decrypt a file. If output_path are not given, then try to use the
        path with a surfix appended. The default automatical file path handling
        is defined here :meth:`windtalker.files.recover_path`

        :param path: path of the file you need to decrypt
        :param output_path: decrypted file output path
        :param overwrite: if True, then silently overwrite output file if exists
        :param stream: if it is a very big file, stream mode can avoid using
          too much memory
        :param enable_verbose: boolean, trigger on/off the help information

def decrypt_file(self,
                     path,
                     output_path=None,
                     overwrite=False,
                     stream=True,
                     enable_verbose=True,
                     **kwargs):
        """
        Decrypt a file. If output_path are not given, then try to use the
        path with a surfix appended. The default automatical file path handling
        is defined here :meth:`windtalker.files.recover_path`

        :param path: path of the file you need to decrypt
        :param output_path: decrypted file output path
        :param overwrite: if True, then silently overwrite output file if exists
        :param stream: if it is a very big file, stream mode can avoid using
          too much memory
        :param enable_verbose: boolean, trigger on/off the help information
        """
        path, output_path = files.process_dst_overwrite_args(
            src=path, dst=output_path, overwrite=overwrite,
            src_to_dst_func=files.get_decrpyted_path,
        )

        self._show("Decrypt '%s' ..." % path, enable_verbose=enable_verbose)
        st = time.clock()
        files.transform(path, output_path, converter=self.decrypt,
                        overwrite=overwrite, stream=stream,
                        chunksize=self._decrypt_chunk_size)
        self._show("    Finished! Elapse %.6f seconds" % (time.clock() - st,),
                   enable_verbose=enable_verbose)

        return output_path