class_docstr: Example messenger onboarding that collects and returns data for use in the real task
  world.
class_docstr_tok: ["Example","messenger","onboarding","that","collects","and","returns","data","for","use","in","the","real","task","world","."]
code: def assign_roles(agents):
      for a in agents:
          a.disp_id = "Agent"
  
imports: from parlai.core.worlds import World
  from parlai.chat_service.services.messenger.worlds import OnboardWorld
label_desc: Use image node_id 3 for calling the MessengerOnboardDataOnboardWorld obj's underlying member method code with example usage: obj.assign_roles(agents) without return types