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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def define(self, id, schema):
 """Add a schema to the list of definition :param id: id of the schema. :param schema: the schema as a dict or a :class:schemabuilder.primitives.Generic :return: reference to schema. :rtype: :class:`schemabuilder.schema.Ref` """

        self.definitions[id] = schema
        self._schema = None
        return self.ref(id)