code: def set_bit_order(self, order):
          
          # Set self._mask to the bitmask which points at the appropriate bit to
          # read or write, and appropriate left/right shift operator function for
          # reading/writing.
          if order == MSBFIRST:
              self._mask = 0x80
              self._write_shift = operator.lshift
              self._read_shift = operator.rshift
          elif order == LSBFIRST:
              self._mask = 0x01
              self._write_shift = operator.rshift
              self._read_shift = operator.lshift
          else:
              raise ValueError('Order must be MSBFIRST or LSBFIRST.')
docs: Set order of bits to be read/written over serial lines.  Should be
          either MSBFIRST for most-significant first, or LSBFIRST for
          least-signifcant first.