More cleanup

    fn stack_len(&self) -> c_int {

        unsafe { OPENSSL_sk_num(self.stack as *mut _) }

    }

    unsafe fn get(&mut self, i: c_int) -> T {

        let ptr = OPENSSL_sk_value(self.stack as *mut _, i);

        T::from_ptr(ptr as *mut _)

    }

}

impl<T: Stackable> Drop for IntoIter<T> {

            if self.idx == self.stack_len() {

                None

            } else {

                let idx = self.idx;

                let ptr = OPENSSL_sk_value(self.stack as *mut _, self.idx);

                self.idx += 1;

                let v = self.get(idx);

                Some(v)

                Some(T::from_ptr(ptr as *mut _))

            }

        }

    }