1 - Semantics - Attributes Grammar (25 points) Using the following grammar write an attributes grammar that can calculate the decimal value of an octal number. Grammar: number = list list = list octal octal octal = '0'|'1'|'2'|'3'|'4'|'5'|'6'|'7' Notes: An octal number consists of octal digits, i.e. O to 7. The following example shows how to convert the octal 67 to its equivalent decimal. The symbol star represents multiplication. 67 = 6*87 + 7* 8 = 6 * 8 + 7 = 55 Questions: 1a - introduce an attribute (4 points) 1b - specify the type of your attribute, i.e. intrinsic, inherited, or synthesized. (5 points) 1c - write the attributes grammar (Syntax rule, Semantic rule, Semantic condition) for every grammar rule. (16 points)