fn skip_spaces(&mut self) {
        while self.current_char == b' ' {
            self.advance();
        }
    }
/// set parser to next non-space character
set parser to next non-space character
set parser to next non - space character
fn skip_spaces(&mut self) {
        while self.current_char == b' ' {
            self.advance();
        }
    }
fn skip_spaces ( & mut self ) { while self . current_char == b' ' { self . advance ( ) ; } }
set parser to next non-space character
set parser to next non - space character
&mut self
&mut self