Extend the Definelang programming language from this chapter such that it supports an undefine declaration. The goal

Question:

Extend the Definelang programming language from this chapter such that it supports an undefine declaration. The goal of adding this new declaration is to clean up the global name space by removing those declarations that are no longer needed for the remainder of the program.

An undefine declaration has the following form: $ (undefine Identifier ) Some example usage of this declaration appears here: $ (define R 8.3145) unit $(/(*