How to use the graphql-transformer-core.stripDirectives function in graphql-transformer-core

delete ctx.nodeMap.Subscription
            includeSubscription = false
        }
        const ops = []
        if (includeQuery) {
            ops.push(makeOperationType('query', queryNode.name.value))
        }
        if (includeMutation) {
            ops.push(makeOperationType('mutation', mutationNode.name.value))
        }
        if (includeSubscription) {
            ops.push(makeOperationType('subscription', subscriptionNode.name.value))
        }
        const schema = makeSchema(ops)
        ctx.putSchema(schema)
        const astSansDirectives = stripDirectives({
            kind: 'Document',
            definitions: Object.keys(ctx.nodeMap).map((k: string) => ctx.getType(k))
        }, ['aws_subscribe', 'aws_auth'])
        const SDL = print(astSansDirectives)
        return SDL;
    }