text: #!/usr/local/bin/python3
  import sys
  
  caser_options = {
      'capitalize': str.capitalize,
      'title': str.title,
      'upper': str.upper,
      'lower': str.lower,
      'exit': quit
  }
  
  options = caser_options.keys()
  
  while True:
      option_prompt = 'Enter a function name ({0}): '.format(', '.join(options))
      string_prompt = 'Enter a string: '
      option_inp = str(input(option_prompt))
      option = caser_options.get(option_inp, None)
      
      if option_inp not in options:
          print("Option not in options list. Please choose one of the following: {0}".format(', '.join(options)))
          continue  
      string_inp = str(input(string_prompt))
      if option_inp == "exit":
          option("Goodbye for now!")
      print(option(string_inp))
     