# File kwartz.rb, line 4172
        def self.parse_expr(expression_str, toppings)
            scanner = Kwartz::Scanner.new(expression_str, toppings)
            parser     = Kwartz::Parser.new(scanner, toppings)
            #node = parser.parse_expression()
            node = parser.parse_assignment()
            if parser.token
                msg = ''
                raise Kwartz::SyntaxError.new(msg, scanner)
            end
            output = node.print_all
            return output
        end