docs: def content_type(transformers, default=None):
      """Returns a different transformer depending on the content type passed in.
         If none match and no default is given no transformation takes place.
  
         should pass in a dict with the following format:
  
              {'[content-type]': transformation_action,
               ...
              }
      """
      transformers = {content_type: auto_kwargs(transformer) if transformer else transformer
                      for content_type, transformer in transformers.items()}
      default = default and auto_kwargs(default)
  
      def transform(data, request):
          transformer = transformers.get(request.content_type.split(';')[0], default)
          if not transformer:
              return data
  
          return transformer(data)
      return transform