/// Advances the position, and returns an empty `Result` whose error
/// indicates that the end of the file has been unexpectedly reached.
/// This allows to use the `self.advance()?;` syntax.
Advances the position, and returns an empty `Result` whose error
indicates that the end of the file has been unexpectedly reached.
This allows to use the `self.advance()?;` syntax.
Advances the position and returns an empty ` Result ` whose error indicates that the end of the file has been unexpectedly reached . This allows to use the ` self . advance () ? ; ` syntax .
fn advance(&mut self) -> Result<(), &'static str> {
        let npos = self.pos + 1;
        self.pos = npos;
        if npos < self.tokens.len() {
            Ok(())
        } else {
            Err("Unexpected end of file.")
        }
    }
fn advance ( & mut self ) -> Result < ( ) , & ' static str > { let npos = self . pos + 1 ; self . pos = npos ; if npos < self . tokens . len ( ) { Ok ( ( ) ) } else { Err ( " " ) } }
Advances the position, and returns an empty `Result` whose error
indicates that the end of the file has been unexpectedly reached.
Advances the position and returns an empty ` Result ` whose error indicates that the end of the file has been unexpectedly reached .
&mut self