lisp_eval_should_be '(prog1 5 (print "foo"))' '"foo"
5' 'prog1'

    _symbol("prog1")

function _evprog1(forms, env, outer_env, d,    rv) {
    if(_is_null(forms))
        return _nil()
    rv = _eval3(_car(forms), env, env, d)
    _evprog(_cdr(forms), env, env, d)
    return rv
}

    else if(car == _symbol("prog1"))
        return _evprog1(_cdr(form), env, env, d+1)