input: Write a python function to check if a number is divisible by another number.
  assert is_divisible(10, 2) == True
  assert is_divisible(15, 3) == True
  assert is_divisible(7, 2) == False
  assert is_divisible(20, 5) == True
output: def is_divisible(num1, num2):
      return num1 % num2 == 0