input: Write a python function to prompt the user for an integer input and handle non-integer inputs gracefully.
  assert handle_input("10")==10
  assert handle_input("abc")=="That's not an integer!"
  assert handle_input("42")==42
output: def handle_input(user_input):
      try:
          return int(user_input)
      except ValueError:
          return "That's not an integer!"