parse_expression
expression_ptr e(parse_expression(true));
expression_ptr true_case = parse_expression();
expression_ptr false_case = parse_expression();
expression_ptr rhs(parse_expression());
expression_ptr &&subexpr = parse_expression();
expression_ptr &&subexpr = parse_expression();
expression_ptr &&subexpr = parse_expression();
expression_ptr &&subexpr = parse_expression();
expression_ptr &&subexpr = parse_expression();
expression_ptr parse_expression(bool stopAtParen=false);
exp = parse_expression(argv[1]);
struct expression *parse_expression(char *str);
master_exp = parse_expression(optarg);