docs: def seek(self, offset, whence=0):
          """Set file's current position."""
          if self._offset:
              if whence == 0:
                  self._fh.seek(self._offset + offset, whence)
                  return
              if whence == 2 and self._size > 0:
                  self._fh.seek(self._offset + self._size + offset, 0)
                  return
          self._fh.seek(offset, whence)