Rust Vec which can contain arbitrary types inrernally casts inputs to Box<UnsafeAny>
.
```rust let mut v = TypeVec::new(); assert!(v.is_empty());
// Can push whatever values. v.push(1); v.push(2.2); v.push("xxx"); v.push(vec![1, 2, 3]);
// Give type hint to specify return type.
asserteq!(v.get::
// getmut
asserteq!(v.get_mut::
// pop
asserteq!(v.pop::