转换类型.
```rust
pub fn teststringtohex() { use iceyeeconvert::Conversion; println!(""); assert!(Conversion::stringtohex("FFF").unwrap() == 0xFFF); assert!(Conversion::stringtohex("1af").unwrap() == 0x1AF); assert!(Conversion::stringtohex("FFFG").iserr()); assert!(Conversion::stringtohex(" Z").iserr()); return; } ```