code: def p_partselect_plus(self, p):
          'partselect : identifier LBRACKET expression PLUSCOLON expression RBRACKET'
          p[0] = Partselect(p[1], p[3], Plus(
              p[3], p[5], lineno=p.lineno(1)), lineno=p.lineno(1))
          p.set_lineno(0, p.lineno(1)f p_partselect_plus(self, p):
          'partselect : identifier LBRACKET expression PLUSCOLON expression RBRACKET'
          p[0] = Partselect(p[1], p[3], Plus(
              p[3], p[5], lineno=p.lineno(1)), lineno=p.lineno(1))
          p.set_lineno(0, p.lineno(1))
docs: partselect : identifier LBRACKET expression PLUSCOLON expression RBRACKET