input: Write a function to handle user input in a loop and break when 'exit' is entered.
  assert handle_user_input(['hello', 'world', 'exit']) == None
  assert handle_user_input(['test', 'python', 'code', 'exit']) == None
  assert handle_user_input(['exit']) == None
output: def handle_user_input(inputs):
      for input_str in inputs:
          if input_str == 'exit':
              break