class_docstr: Example messenger onboarding world for chat task, displays intro and explains
  instructions.
class_docstr_tok: ["Example","messenger","onboarding","world","for","chat","task",",","displays","intro","and","explains","instructions","."]
code: def generate_world(opt, agents):
      return MessengerChatOnboardWorld(opt, agents[0])
  
imports: from parlai.core.worlds import World
  from parlai.chat_service.services.messenger.worlds import OnboardWorld
label_desc: Use image node_id 2 for calling the MessengerChatOnboardWorld obj's underlying member method code with example usage: obj.generate_world(opt, agents) and returns: MessengerChatOnboardWorld