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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 add_schema(self, schema):
 """ Merge in a JSON schema. This can be a ``dict`` or another ``SchemaBuilder`` :param schema: a JSON Schema .. note:: There is no schema validation. If you pass in a bad schema, you might get back a bad schema. """

        if isinstance(schema, SchemaBuilder):
            schema_uri = schema.schema_uri
            schema = schema.to_schema()
            if schema_uri is None:
                del schema['$schema']
        elif isinstance(schema, SchemaNode):
            schema = schema.to_schema()

        if '$schema' in schema:
            self.schema_uri = self.schema_uri or schema['$schema']
            schema = dict(schema)
            del schema['$schema']
        self._root_node.add_schema(schema)