Here’s your code cleaned up and extended with `push_str`, `push`, `concat`, and `join` examples in a clear, idiomatic Rust style:

(concat , append) This keeps original data and adds new text after it.

Rust Standard Library_training 001_ Concatenating strings(All 11 Rust code examples)

String Method `format!`, `+`, `push_str`, `push`, `concat`, `join`

default 사용법 & 반복적이고 귀찮은 default를 꼭 만들자

std rust arrays map, free function

rust Standard Library(std) training

API of Vulkan.(그림으로 Vulkan이해하기)