code: def _source_is_newer(src_fs, src_path, dst_fs, dst_path):
      # type: (FS, Text, FS, Text) -> bool
      
      try:
          if dst_fs.exists(dst_path):
              namespace = ("details", "modified")
              src_modified = src_fs.getinfo(src_path, namespace).modified
              if src_modified is not None:
                  dst_modified = dst_fs.getinfo(dst_path, namespace).modified
                  return dst_modified is None or src_modified > dst_modified
          return True
      except FSError:  # pragma: no cover
          # todo: should log something here
          return True
docs: Determine if source file is newer than destination file.
  
      Arguments:
          src_fs (FS): Source filesystem (instance or URL).
          src_path (str): Path to a file on the source filesystem.
          dst_fs (FS): Destination filesystem (instance or URL).
          dst_path (str): Path to a file on the destination filesystem.
  
      Returns:
          bool: `True` if the source file is newer than the destination
          file or file modification time cannot be determined, `False`
          otherwise.