diff --git a/Examples/src/HeapView/heapViewTraits.hpp b/Examples/src/HeapView/heapViewTraits.hpp
new file mode 100644
index 000000000..673de6812
--- /dev/null
+++ b/Examples/src/HeapView/heapViewTraits.hpp
@@ -0,0 +1,45 @@
+//
+// Created by forma on 20/06/23.
+//
+
+#ifndef EXAMPLES_HEAPVIEWTRAITS_HPP
+#define EXAMPLES_HEAPVIEWTRAITS_HPP
+#include <vector>
+#include <optional>
+
+
+namespace apsc
+{
+
+/*!
+@brief Traits for the heapView class
+@tparam DataElementType The type of the elements stored in the heap
+*/
+template <class DataElementType>
+struct heapViewTraits
+{
+  //! The type of the index
+  using Index = typename std::vector<DataElementType>::size_type;
+  //! The type of the vector storing the data
+  using DataVector = std::vector<DataElementType>;
+  //! The type of the indixes of the heap (it is the same as the type of the indexes of the data vector)
+  using DataIndex = Index;
+  /*! The type of the elements stored in the heap.
+  * It is the same as the type of the elements stored in the data vector
+  * @note We need a comparison operator on this type
+  */ 
+  using ElementType = DataElementType;
+  /*! The internal structure keeping the indexes of the heap
+   * 
+   * HeapIndex(i) returns the index of the i-th element in the heap
+   */
+  using HeapIndex = std::vector<Index>;
+  /*! An internal structure storing the indexes of the data vector
+   * HeapIter(i) returns the index of the i-th heap element in the data vector
+   * We have HeapIndex(HeapIter(i))=i if i is a valid index of the heap 
+  */
+ using HeapIter = std::vector<std::optional<Index>>;
+};
+
+} // namespace apsc
+#endif // EXAMPLES_HEAPVIEWTRAITS_HPP
diff --git a/Examples/src/RKFSolver/ButcherRKF.hpp b/Examples/src/RKFSolver/ButcherRKF.hpp
index 145db6d05..777cfce68 100644
--- a/Examples/src/RKFSolver/ButcherRKF.hpp
+++ b/Examples/src/RKFSolver/ButcherRKF.hpp
@@ -55,6 +55,8 @@ template <unsigned int NSTAGES> struct ButcherArray
   /*!
    * Check if it correspond to an implicit RK scheme
    * @return true if implicit
+   * @todo try to do it in the constructor. I need to check if it is possible to
+   * maintain it constexpr
    *
    */
   constexpr bool
diff --git a/Examples/src/STL/Optional/main_optional.cpp b/Examples/src/STL/Optional/main_optional.cpp
index 5c3f35181..1b648385b 100644
--- a/Examples/src/STL/Optional/main_optional.cpp
+++ b/Examples/src/STL/Optional/main_optional.cpp
@@ -24,6 +24,7 @@ countValid(V const &v)
     if(x)
       ++count;
   });
+
   std::cout << "The container has " << count << " valid elements:\n";
   for(auto &x : v)
     if(x) // valid
@@ -52,7 +53,9 @@ main()
     std::cout << "v[2] stores no value" << std::endl;
   v[2] = 20.0;
   countValid(v);
-  if(v[2].has_value())
+
+  // You may also exploit the fact that a std::optional<T> converts to bool
+  if(v[2])
     std::cout << "v[2] stores " << v[2].value() << std::endl;
   else
     std::cout << "v[2] stores no value" << std::endl;