input: Write a function to create a simple chatbot using Python and state diagrams. The chatbot should initialize with a starting state and allow the user to transition between states based on their inputs. If the user input is not recognized, the chatbot should prompt the user to try again. The conversation should end when the chatbot reaches a state with no replies.
  
  assert chatbot_simulation()=='''
  =========================
  Conversation:
  Hello! How can I help you?
  I need some advice
  Sure, what kind of advice do you need?
  Career advice
  It is always a good idea to research the field you are interested in and creating a plan to learn the skills that are required. Make sure to contact professionals in the field to understand their experience.
  Goodbye!
  '''
output: def chatbot_simulation():
      states = {
          'start': {
              'message': 'Hello! How can I help you?',
              'replies': {
                  'I need some advice': 'advice'
              }
          },
          'advice': {
              'message': 'Sure, what kind of advice do you need?',
              'replies': {
                  'Career advice': 'career_advice'
              }
          },
          'career_advice': {
              'message': 'It is always a good idea to research the field you are interested in and creating a plan to learn the skills that are required. Make sure to contact professionals in the field to understand their experience.',
              'replies': {}
          }
      }
      
      current_state = 'start'
      conversation = "=========================\nConversation:\n"
      
      while states[current_state]['replies']:
          conversation += states[current_state]['message'] + "\n"
          user_input = input(states[current_state]['message'] + "\n")
          if user_input in states[current_state]['replies']:
              current_state = states[current_state]['replies'][user_input]
          else:
              conversation += "I didn't understand that. Please try again.\n"
      
      conversation += states[current_state]['message'] + "\nGoodbye!\n"
      return conversation