input: Write a python function to check if a number is divisible by another number and return a corresponding message.
  assert check_divisibility(10, 2) == "The number 10 is divisible by 2."
  assert check_divisibility(10, 3) == "The number 10 is not divisible by 3."
  assert check_divisibility(15, 5) == "The number 15 is divisible by 5."
  assert check_divisibility(15, 4) == "The number 15 is not divisible by 4."
output: def check_divisibility(num, divisor):
      if num % divisor == 0:
          return f"The number {num} is divisible by {divisor}."
      else:
          return f"The number {num} is not divisible by {divisor}."