code: def seek(self, position, modifier=0):
          
          os.lseek(self._fileno, position, modifier)
  
          # clear out the buffer
          buf = self._rbuf
          buf.seek(0)
          buf.truncate()
docs: move the cursor on the file descriptor to a different location
  
          :param position:
              an integer offset from the location indicated by the modifier
          :type position: int
          :param modifier:
              an indicator of how to find the seek location.
  
              - ``os.SEEK_SET`` means start from the beginning of the file
              - ``os.SEEK_CUR`` means start wherever the cursor already is
              - ``os.SEEK_END`` means start from the end of the file
  
              the default is ``os.SEEK_SET``