code: public function cache($duration = true, $dependency = null)
      {
          $this->queryCacheDuration = $duration;
          $this->queryCacheDependency = $dependency;
          return $this;
      }
docs: Enables query cache for this Query.
  @param int|true $duration the number of seconds that query results can remain valid in cache.
  Use 0 to indicate that the cached data will never expire.
  Use a negative number to indicate that query cache should not be used.
  Use boolean `true` to indicate that [[Connection::queryCacheDuration]] should be used.
  Defaults to `true`.
  @param \yii\caching\Dependency $dependency the cache dependency associated with the cached result.
  @return $this the Query object itself
  @since 2.0.14