input: Write a function to get larger number divisible by smaller number.
  assert get_larger_number_divisible_by_smaller(10, 20) == 20
  assert get_larger_number_divisible_by_smaller(15, 5) == 15
  assert get_larger_number_divisible_by_smaller(18, 4) == None
  assert get_larger_number_divisible_by_smaller(12, 36) == 36
output: def get_larger_number_divisible_by_smaller(a, b):
      if a > b:
          if a % b == 0:
              return a
      else:
          if b % a == 0:
              return b
      return None