def lift_middle_child(in_tree):
        (A, (B,), (C,), (D,)) = in_tree
    
        return (C, (B,), (D,))

print lift_middle_child(('A', ('B',), ('C',), ('D',))) # could use lists too

def compose2(a,b): # might want to get this from the functional library
    return lambda *x: a(b(*x))

def compose(*funcs): #compose(a,b,c) = a(b(c(x))) - you might want to reverse that
    return reduce(compose2,funcs)

def reverse_children(in_tree):
    return in_tree[0:1] + in_tree[1:][::-1] # slightly cryptic, but works for anything subscriptable

lift_and_reverse = compose(reverse_children,lift_middle_child) # right most function applied first - if you find this confusing, reverse order in compose function.

print lift_and_reverse(('A', ('B',), ('C',), ('D',)))