code: def posix_props(self, prop, in_group=False):
          
  
          try:
              if self.is_bytes or not self.unicode:
                  pattern = _uniprops.get_posix_property(
                      prop, (_uniprops.POSIX_BYTES if self.is_bytes else _uniprops.POSIX)
                  )
              else:
                  pattern = _uniprops.get_posix_property(prop, _uniprops.POSIX_UNICODE)
          except Exception:
              raise ValueError('Invalid POSIX property!')
          if not in_group and not pattern:  # pragma: no cover
              pattern = '^%s' % ('\x00-\xff' if self.is_bytes else _uniprops.UNICODE_RANGE)
  
          return [pattern]
docs: Insert POSIX properties.
  
          Posix style properties are not as forgiving
          as Unicode properties.  Case does matter,
          and whitespace and '-' and '_' will not be tolerated.