code: def calculate_etag(file_path):
          
          stat = file_path.stat()
          etag = "%x-%x" % (stat.st_mtime_ns, stat.st_size)
          return etag
docs: Calculate an etag value
  
          Args:
              a_file (pathlib.Path): The filepath to the
  
          Returns:
              String of the etag value to be sent back in header