Update Workflow.h

Author: Barenboim

src/factory/Workflow.h

@@ -258,11 +258,11 @@ class ParallelWork : public ParallelTask
 	size_t size() const { return this->subtasks_nr; }
 
 public:
-	SeriesWork *begin() { return this->series_at(0); }
-	SeriesWork *end() { return this->all_series + this->subtasks_nr;}
+	SeriesWork **begin() { return this->all_series; }
+	SeriesWork **end() { return this->all_series + this->subtasks_nr; }
 
-	const SeriesWork *begin() const { return this->series_at(0);}
-	const SeriesWork *end() const { return this->all_series + this->subtasks_nr;}
+	const SeriesWork **begin() const { return this->all_series; }
+	const SeriesWork **end() const { return this->all_series + this->subtasks_nr; }
 
 public:
 	void set_callback(parallel_callback_t callback)