Macro def_as_mut

def_as_mut!() { /* proc-macro */ }

this macro will define macro as_mut

example:

def_as_mut!();
 
fn main() {
    let mut example = Sub::new("data".to_string());
    as_mut!(example).set_data("modified".to_string());
    assert_eq!(example.get_data(), "modified".to_string());
}