grapher/lib/exposure/extension.js

import Exposure from './exposure.js';

Object.assign(Mongo.Collection.prototype, {
    expose(config) {
        if (!Meteor.isServer) {
            throw new Meteor.Error(
                'not-allowed',
                `You can only expose a collection server side. ${this._name}`
            );
        }

        new Exposure(this, config);
    },
});