2. (6 points). Consider the following BNF grammar of expressions: : := I + I - * where and correspond to nubs and (program) variables, respectively This gram does not impose the proper precedence between + and *. Without changing the pr- ductions, introduce appropriate attributes, evaluation rules, and conditions such that the proper prece- dence is enforced (i.e., parse trees that do not have the proper precedence, although legal according to the BNF productions, are ruled out by having one or more of the conditions evaluating to false 2. (6 points). Consider the following BNF grammar of expressions: : := I + I - * where and correspond to nubs and (program) variables, respectively This gram does not impose the proper precedence between + and *. Without changing the pr- ductions, introduce appropriate attributes, evaluation rules, and conditions such that the proper prece- dence is enforced (i.e., parse trees that do not have the proper precedence, although legal according to the BNF productions, are ruled out by having one or more of the conditions evaluating to false