> (lambda (x) x)
#<procedure>
> (+ 3 4)
7
> lambda
. lambda: bad syntax in: lambda
> ((lambda (x) x) 3)
3
> ((lambda (x) x) +)
#<procedure:+>
> (((lambda (x) x) +) 3 4 )
7
> ((lambda (x) (x 3))(lambda (y) (+ y 1)))
4
>

> (flatten2 '((((a) (b) c) d) e))
>(flatten2 '((((a) (b) c) d) e))
>(flatten2 '(((a) (b) c) d e))
>(flatten2 '((a) (b) c d e))
>(flatten2 '(a (b) c d e))
> (flatten2 '((b) c d e))
> (flatten2 '(b c d e))
> >(flatten2 '(c d e))
> > (flatten2 '(d e))
> > >(flatten2 '(e))
> > > (flatten2 '())
< < < '()
< < <'(e)
< < '(d e)
< <'(c d e)
< '(b c d e)
<'(a b c d e)
'(a b c d e)
> (flatten2 '((((((a))))) b))
>(flatten2 '((((((a))))) b))
>(flatten2 '(((((a)))) b))
>(flatten2 '((((a))) b))
>(flatten2 '(((a)) b))
>(flatten2 '((a) b))
>(flatten2 '(a b))
> (flatten2 '(b))
> >(flatten2 '())
< <'()
< '(b)
<'(a b)
'(a b)
> (flatten '(((((a)))) b))
>(flatten '(((((a)))) b))
> (flatten '((((a)))))
> >(flatten '(((a))))
> > (flatten '((a)))
> > >(flatten '(a))
> > > (flatten '())
< < < '()
< < <'(a)
> > >(flatten '())
< < <'()
< < '(a)
> > (flatten '())
< < '()
< <'(a)
> >(flatten '())
< <'()
< '(a)
> (flatten '(b))
> >(flatten '())
< <'()
< '(b)
<'(a b)
'(a b)
>

> (arithmetic 3 +)
45
> (arithmetic 3 eq?)
#f
> (arithmetic 3 cons)
'(3 . 42)
>