code: public <T extends Pointer> T getHelperWorkspace(String key){
          return helperWorkspacePointers == null ? null : (T)helperWorkspacePointers.get(key);
      }
docs: Get the pointer to the helper memory. Usually used for CUDNN workspace memory sharing.
  NOTE: Don't use this method unless you are fully aware of how it is used to manage CuDNN memory!
  Will (by design) throw a NPE if the underlying map (set from MultiLayerNetwork or ComputationGraph) is not set.
  
  @param key Key for the helper workspace pointer
  @param <T> Pointer type
  @return Pointer for that key, or null if none exists