pub fn swap_top(&mut self) {
        let a = self.pop();
        let b = self.pop();
        self.push(a);
        self.push(b);
    }
// swap_top takes the top two elements from the stack and reverses them
swap_top takes the top two elements from the stack and reverses them
swap_top takes the top two elements from the stack and reverses them
pub fn swap_top(&mut self) {
        let a = self.pop();
        let b = self.pop();
        self.push(a);
        self.push(b);
    }
pub fn swap_top ( & mut self ) { let a = self . pop ( ) ; let b = self . pop ( ) ; self . push ( a ) ; self . push ( b ) ; }
swap_top takes the top two elements from the stack and reverses them
swap_top takes the top two elements from the stack and reverses them
&mut self
&mut self