text: from typing import List
  
  from pybuses import CommandBus
  
  
  # Firstly, create command class
  class MakeSandwich:
      def __init__(self, ingredients: List[str]) -> None:
          self.ingredients = ingredients
  
  
  # Then create callable responsible for handling command.
  # It must accept only one argument and is required to have type annotation for it.
  def sandwich_maker(command: MakeSandwich) -> None:
      print(f'Making sandwich with {command.ingredients}!')
  
  
  # finally, register the handler by subscribing
  command_bus = CommandBus()
  command_bus.subscribe(sandwich_maker)
  command_bus.handle(MakeSandwich(['cheese', 'ham']))
  