fn foo(b int, a mut []int) {
a[0] = 7
a << 4
}
// TODO
fn test_mut() {
mut numbers := [1,2,3]
foo(7, mut numbers)
//assert a.len == 4
assert numbers[0] == 7
//assert a[3] == 4
n := 1
mut b := &n
*b = 10
//mut b := mut a
//b = 10