text: import { Mongo } from 'meteor/mongo';
  import SimpleSchema from 'simpl-schema';
  import { Tracker } from 'meteor/tracker';
  
  /** Define a Mongo collection to hold the data. */
  const Listings = new Mongo.Collection('Listings');
  
  /** Define a schema to specify the structure of each document in the collection. */
  const ListingsSchema = new SimpleSchema({
    seller: String,
    price: Number,
    ISBN: String,
    description: String,
    binding: {
      type: String,
      allowedValues: ['loose leaf', 'spiral', 'paperback', 'hardcover'],
      defaultValue: 'loose leaf',
    },
  }, { tracker: Tracker });
  
  /** Attach this schema to the collection. */
  Listings.attachSchema(ListingsSchema);
  
  /** Make the collection and schema available to other code. */
  export { Listings, ListingsSchema };
  