Register a definition to the registry. Existing definitions are
        replaced silently.

        :param name: The name which can be used as reference in a validation
                     schema.
        :type name: :class:`str`
        :param definition: The definition.
        :type definition: any :term:`mapping`

def add(self, name, definition):
        """ Register a definition to the registry. Existing definitions are
        replaced silently.

        :param name: The name which can be used as reference in a validation
                     schema.
        :type name: :class:`str`
        :param definition: The definition.
        :type definition: any :term:`mapping` """
        self._storage[name] = self._expand_definition(definition)