code: def p_value_paren(self, tree):
          ''' V ::= value ( LPAREN V RPAREN )'''
          tree.value = convertstr(tree[1].value)
          tree.svalue = "(%s)"%str(tree[1].valuef p_value_paren(self, tree):
          ''' V ::= value ( LPAREN V RPAREN )'''
          tree.value = convertstr(tree[1].value)
          tree.svalue = "(%s)"%str(tree[1].value)
docs: V ::= value ( LPAREN V RPAREN )