Use the following attribute grammar to answer the questions 1. Syntax rule: --> = 2. Syntax rule: --> [2] + [3] Predicate: [2].actual_type == [3].actual_type 3. Syntax rule: --> 4. Syntax rule: --> A | B | C Semantic rule: .actual_type <-- look-up(.string) a) Draw a fully attributed parse tree for the sentence C = C + B, assuming that B has type int, and C has type int. b) According to the attribute grammar, is this sentence valid?