Create a function that takes in the sum and age difference of two people, calculates their individual ages, and returns a pair of values (oldest age first) if those exist or `null/None` if:

* `sum < 0`
* `difference < 0`
* Either of the calculated ages come out to be negative

Difficulty: EASY
Starter code: def get_ages(sum_, difference):
	

Solutions:
def get_ages(a, b):
	x = (a + b) / 2
	y = (a - b) / 2
	return None if a < 0 or b < 0 or x < 0 or (y < 0) else (x, y)


def get_ages(s, diff):
	(older, younger) = (s / 2 + diff / 2, s / 2 - diff / 2)
	if older >= younger >= 0:
		return (older, younger)


def get_ages(sum_, difference):
	a = (sum_ + difference) / 2
	b = sum_ - a
	if 0 <= b <= a:
		return (a, b)


def get_ages(a, b):
	(x, y) = ((a + b) / 2, (a - b) / 2)
	if a >= 0 and b >= 0 and (x >= 0) and (y >= 0):
		return (x, y)


def get_ages(add, dif):
	return None if any((n < 0 for n in (add, dif, add - dif))) else ((add + dif) / 2, (add - dif) / 2)


def get_ages(sum_, difference):
	x = (sum_ + difference) / 2
	y = sum_ - x
	return None if any((e < 0 for e in (x, y, sum_, difference))) else (x, y)


def get_ages(sum_, difference):
	ret = ((sum_ + difference) / 2, (sum_ - difference) / 2)
	if difference < 0 or (ret[1] < 0 or ret[0] < 0):
		return None
	else:
		return ret


def get_ages(sum, difference):
	age1 = (sum + difference) / 2
	age2 = sum - age1
	if sum < 0 or difference < 0 or age1 < 0 or (age2 < 0):
		return None
	if age1 > age2:
		return (age1, age2)
	else:
		return (age2, age1)


get_ages = lambda s, d: (lambda *a: None if any((x < 0 for x in (*a, s, d))) else a)((s + d) / 2, (s - d) / 2)