How to use the fast-json-patch.unobserve function in fast-json-patch

store.close = function close(returnError) {
			jsonpatch.unobserve(store.data, observer);

			lockFile.unlock(storePath + LOCK_FILE_EXTENSION, function (error) {
				if (error) {
					error.stacktrace = new Error().stack;
					store.emit('error', error);
					if (returnError) { returnError(error); } else { throw error; }
					return;
				}

				store.emit('closed');

				returnError && returnError();
			});
		};

unobserve() {
    if(!this.observer) {
      throw new Error('Not observing changes');
    }
    jsonpatch.unobserve(this.doc, this.observer);
    this.observer = null;
  }

store.close = function close(returnError) {
				
				jsonpatch.unobserve(store.data, observer);

				lockFile.unlock(path + LOCK_FILE_EXTENSION, function (error) {
					if (error) {
						if (returnError) { returnError(error); } else { throw error; }
						return;
					}
					returnError && returnError();
				});
			};