Research to write down the rule of a variable identifier in the following programming languages and write down the regular grammar for that rule. For example, as elaborated in the class, the rule of a variable identifier in C is "start either by_, or any alphabetic character, and then follow either by_, any alphabetic character, or number", and its regular grammar is: La-zA-Z][a-zA-ZO-9]* a. JavaScript i. Rule: ii. Regular grammar b. PHP i. Rule: ii. Regular grammar: c. Python i. Rule: li. Regular grammar: d. GoLang i. Rule: ii. Regular grammar