docs: def _update_seek(self, offset, whence):
          """
          Update seek value.
  
          Args:
              offset (int): Offset.
              whence (int): Whence.
  
          Returns:
              int: Seek position.
          """
          with self._seek_lock:
              if whence == SEEK_SET:
                  self._seek = offset
              elif whence == SEEK_CUR:
                  self._seek += offset
              elif whence == SEEK_END:
                  self._seek = offset + self._size
              else:
                  raise ValueError('whence value %s unsupported' % whence)
          return self._seek