input: Write a function to process a command string and return the corresponding output.
  assert process_command("Taking a break") == "Taking a five minute break"
  assert process_command("Starting work") == "Invalid command"
  assert process_command("Lunch time") == "Invalid command"
output: def process_command(command):
      if command == "Taking a break":
          return "Taking a five minute break"
      else:
          return "Invalid command"