code: def register_post_processor(func):
      
  
      global POST_PROCESSORS
  
      key = func.__name__
      POST_PROCESSORS[key] = func
      return func
docs: Register a post processor function to be run as the final step in
      serialization. The data passed in will already have gone through the
      sideloading processor.
  
      Usage:
          @register_post_processor
          def my_post_processor(data):
              # do stuff with `data`
              return data