docs: def _get_checksum(path):
      """ Generates a md5 checksum of the file at the specified path.
  
          `path`
              Path to file for checksum.
  
          Returns string or ``None``
          """
  
      # md5 uses a 512-bit digest blocks, let's scale by defined block_size
      _md5 = hashlib.md5()
      chunk_size = 128 * _md5.block_size
  
      try:
          with open(path, 'rb') as _file:
              for chunk in iter(lambda: _file.read(chunk_size), ''):
                  _md5.update(chunk)
          return _md5.hexdigest()
  
      except IOError:
          return None