docs: def p_side(self, idx, sidedness):
          """Acceptable values for *sidedness* are "auto", "pos",
          "neg", and "two"."""
          dsideval = _dside_names.get(sidedness)
          if dsideval is None:
              raise ValueError('unrecognized sidedness "%s"' % sidedness)
  
          p = self._pinfob
          p[idx] = (p[idx] & ~PI_M_SIDE) | dsideval
          return self