SESSION quotes
// If you get the object stored in the session in this way, it is actually a reference
// If you modify the value in myDataSet, the value in the session will change accordingly.
// ...
MyDataSet = (Dataset) session ["Dataset"];
// ...
// So we have to use the copy () method to get a copy of the object.
// This way, when we change the value in MyDataSet, the value in the session will not change.
// ...
MyDataSet = ((Dataset) Session ["Dataset"]). Copy ();
// ...
