cons(a, b) constructs a pair, and car(pair) and cdr(pair) returns the first and last element of that pair.
Given this implementation of cons below, implement car and cdr.
>>> def cons(a, b):
... def pair(f):
... return f(a, b)
... return pair
>>> car, cdr = coding_problem_05()
>>> car(cons('first', 'last')) == 'first'
True
>>> cdr(cons('first', 'last')) == 'last'
True