text: const dbConnection = require("./mongoConnection");
  
  /* This will allow you to have one reference to each collection per app */
  /* Feel free to copy and paste this this */
  let getCollectionFn = (collection) => {
      let _col = undefined;
  
      return () => {
          if (!_col) {
              _col = dbConnection().then(db => {
                  return db.collection(collection);
              });
          }
  
          return _col;
      }
  }
  
  /* Now, you can list your collections here: */
  module.exports = {
      users: getCollectionFn("users"),
      categories: getCollectionFn("categories")
  };