del(keys) {
		this.metrics.increment(METRIC.MOLECULER_CACHER_DEL_TOTAL);
		const timeEnd = this.metrics.timer(METRIC.MOLECULER_CACHER_DEL_TIME);

		keys = Array.isArray(keys) ? keys : [keys];
		keys.forEach(key => {
			this.cache.delete(key);
			this.logger.debug(`REMOVE ${key}`);
		});
		timeEnd();

		return this.broker.Promise.resolve();
	}
Delete a key from cache

@param {string|Array<string>} key
@returns {Promise}

@memberof MemoryCacher