[fix] producers helper function always retrieved constant producer, by default...

Fix aidge_learning#11 (closed)

include/aidge/recipes/GraphViewHelper.hpp

@@ -22,11 +22,12 @@
 namespace Aidge {
 
 /**
- * @brief Getter for every Producer operator in a GraphView.
+ * @brief Getter for every Tensor held by a Producer operator in a GraphView.
  * @param graphview GraphView instance where Producers should be searched.
+ * @param constant If true, Producer with attribute ``constant=true`` are also included in the returned set, default=false
  * @return std::set<std::shared_ptr<Node>>
  */
-std::set<std::shared_ptr<Tensor>> producers(std::shared_ptr<GraphView> graphview);
+std::set<std::shared_ptr<Tensor>> producers(std::shared_ptr<GraphView> graphview, bool constant=false);
 
 
 // TODO: change for every Tensor of Operator Producer not constant