Write the following functions on lists in Scheme. The semantics of the functions is described through examples. (1) (define flatten (lambda (l) ... )) ... (flatten ’(a ((b) (c d) (((e --> ’(a b c d e) (2) (define rev (lambda (l) ...)) ... (rev ’(e((b)(c d)(((f --> ’f)))(c d)(b))e)