fn mark_productive(&mut self) {
                if let Some(top) = self.stack.last_mut() {
                    top.1 = true;
                }
            }
// Mark the most inner loop as being productive, if one exists.
Mark the most inner loop as being productive, if one exists.
Mark the most inner loop as being productive if one exists .
fn mark_productive(&mut self) {
                if let Some(top) = self.stack.last_mut() {
                    top.1 = true;
                }
            }
fn mark_productive ( & mut self ) { if let Some ( top ) = self . stack . last_mut ( ) { top . 1 = true ; } }
Mark the most inner loop as being productive, if one exists.
Mark the most inner loop as being productive if one exists .
&mut self