fn main(){
println!("hello world");
}
Function are fn
println has a ! after it, as it's a macro and not a function.
And a semicolon ; after each statement.
No need to return 0 at end of main()
let x=1; x=2; //<-- can't let x mut=1; //<-- put a mut after variable name to reassign it later. x=2; //
Variables are declared with let