Struct Bag Copy item path

use sdd::Bag;

let bag: Bag<usize, 16> = Bag::new();

use sdd::Bag;

let bag: Bag<usize> = Bag::default();

bag.push(11);

use sdd::Bag;

let bag: Bag<usize, 1> = Bag::new();

assert!(bag.try_push(11).is_ok());
assert_eq!(bag.try_push(17), Err(17));

use sdd::Bag;

let bag: Bag<usize> = Bag::default();

bag.push(37);

assert_eq!(bag.pop(), Some(37));
assert!(bag.pop().is_none());

use sdd::Bag;

let bag: Bag<usize> = Bag::default();

bag.push(7);
bag.push(17);
bag.push(37);

assert_eq!(bag.pop_all(0, |a, v| a + v), 61);

bag.push(47);
assert_eq!(bag.pop(), Some(47));
assert!(bag.pop().is_none());
assert!(bag.is_empty());

use sdd::Bag;

let bag: Bag<usize> = Bag::default();
assert_eq!(bag.len(), 0);

bag.push(7);
assert_eq!(bag.len(), 1);

for v in 0..64 {
   bag.push(v);
}
bag.pop();
assert_eq!(bag.len(), 64);

use sdd::Bag;

let bag: Bag<usize> = Bag::default();
assert!(bag.is_empty());

bag.push(7);
assert!(!bag.is_empty());

assert_eq!(bag.pop(), Some(7));
assert!(bag.is_empty());

use sdd::Bag;

let mut bag: Bag<usize> = Bag::default();

bag.push(3);
bag.push(3);

assert_eq!(bag.iter_mut().count(), 2);
bag.iter_mut().for_each(|e| { *e += 1; });

assert_eq!(bag.pop(), Some(4));
assert_eq!(bag.pop(), Some(4));
assert!(bag.pop().is_none());