* stage constant folding, where, witht he help of the AST, operator
* usages can be constant folded. Then there is the constant folding
* in the IR for things like eliding if statements, can occur.
* stage constant folding, where, witht he help of the AST, operator
* usages can be constant folded. Then there is the constant folding
* in the IR for things like eliding if statements, can occur.