Functions With No Arguments And No Return Value

The formula for functions that take no arguments and return no values is:

1. The fn keyword
2. A name
3. An empty set of () parenthesis
4. A set of {} curly brackets surrounding the function's code block

For example:

fn widget() {
  println!("this is widget");
}

Calling functions without arguments is done using its name followed by empty (), like:

widget();