code: def register(self, klass, callback, name="default"):
          
          if klass not in self._definitions:
              self._definitions[klass] = {}
  
          self._definitions[klass][name] = callback
docs: Register a class with a function.
  
          :param klass: The class
          :type klass: class
  
          :param callback: The callable
          :type callback: callable
  
          :param name: The short name
          :type name: str