fn say_hello(name: String) { println!("hello {name} !!!"); } fn sum(a: i32, b: i32) -> i32 { return a + b; } fn main() { println!("Hello, world!"); println!("aaa {}", "bbb"); let mut a: i32 = 1; println!("a is :{}", a); a = 2; println!("a …