code: def get_username(details, backend, response, *args, **kwargs):
      
  
      user = details.get('user')
      if not user:
          user_uuid = kwargs.get('uid')
          if not user_uuid:
              return
  
          username = uuid_to_username(user_uuid)
      else:
          username = user.username
  
      return {
          'username': username
      }
docs: Sets the `username` argument.
  
      If the user exists already, use the existing username. Otherwise
      generate username from the `new_uuid` using the
      `helusers.utils.uuid_to_username` function.