code: def _read(self):
          
          filepos = self._fp.tell()
          if filepos < 1:
              return ""
          destpos = max(filepos - self._chunk_size, 0)
          self._fp.seek(destpos)
          buf = self._fp.read(filepos - destpos)
          self._fp.seek(destpos)
          return buf
docs: Reads and returns a buffer reversely from current file-pointer position.
  
          :rtype : str