input: Write a function to take a number as input and return a list of all its divisors. If the input number is 0, return a message stating that zero has no divisors.
  assert get_divisors(10)==[1, 2, 5, 10]
  assert get_divisors(0)=='Zero has no divisors.'
  assert get_divisors(17)==[1, 17]
  assert get_divisors(100)==[1, 2, 4, 5, 10, 20, 25, 50, 100]
  assert get_divisors(1)==[1]
output: def get_divisors(n):
      if n == 0:
          return 'Zero has no divisors.'
      divisors = [i for i in range(1, n + 1) if n % i == 0]
      return divisors