Function function 

pub fn function(
    name: &str,
    parameters: Vec<GeneratedToken>,
    result: Vec<GeneratedToken>,
    body: Vec<GeneratedToken>,
) -> Result<Vec<GeneratedToken>, Overflow>

One conventional fn name(parameters) -> result { body } item.

The visibility is the caller’s and is written before this, so one operation spells a private function, a pub one, and a pub(crate) one. This narrow convenience accepts one flattened parameter run and delegates all function framing to function_signature and function_item.

Errors

Returns Overflow where the parameter list or body outgrows the declared generated-token magnitude.