docs: def _fuzz_data_file(self, data_file):
          """Generate fuzzed variant of given file.
  
          :param data_file: path to file to fuzz.
          :type data_file: str
          :return: path to fuzzed file.
          :rtype: str
          """
          buf = bytearray(open(os.path.abspath(data_file), 'rb').read())
          fuzzed = fuzzer(buf, self.fuzz_factor)
          try:
              _, fuzz_output = mkstemp(prefix='fuzzed_')
              open(fuzz_output, 'wb').write(fuzzed)
          finally:
              pass
          return fuzz_output