docs: def _md5(path: pathlib.PurePath):
          """
          Calculate the MD5 checksum of a file.
  
          :param path: The path of the file whose checksum to calculate.
          :return: The lowercase hex representation of the file's MD5
                      checksum, exactly 32 chars long.
          """
          hash_ = hashlib.md5()
          with open(path, 'rb') as f:
              for chunk in iter(lambda: f.read(4096), b''):
                  hash_.update(chunk)
          return hash_.hexdigest()