code: function findOrCreate(params, cb) {
  	/* istanbul ignore next */
  	if (typeof cb !== 'function') {
  		throw new Error('Callback must be a function');
  	}
  
  	db.findOne(params, (err, doc) => {
  		/* istanbul ignore next: hard-to-invoke error */
  		if (err) {
  			cb(err);
  			return;
  		}
  
  		if (doc) {
  			cb(null, doc.token);
  		} else {
  			params.token = uuid();
  			db.insert(params, (err, newDoc) => {
  				/* istanbul ignore next: hard-to-invoke error */
  				if (err) {
  					cb(err);
  					return;
  				}
  
  				cb(null, newDoc.token);
  			});
  		}
  	});
  }
docs: Attempt to find an existing token for the provided search parmeters. If found, return that token. If not, make a new token (just a uuid string).