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 | use crate::tokenizer::{Event, TokenType};
/// To do.
pub fn opt(events: &[Event], index: usize, token_types: &[TokenType]) -> usize {
    skip_opt_with_direction(events, index, token_types, true)
}
/// To do.
pub fn opt_back(events: &[Event], index: usize, token_types: &[TokenType]) -> usize {
    skip_opt_with_direction(events, index, token_types, false)
}
/// To do.
fn skip_opt_with_direction(
    events: &[Event],
    index: usize,
    token_types: &[TokenType],
    forward: bool,
) -> usize {
    let mut index = index;
    while index < events.len() {
        let current = &events[index].token_type;
        if !token_types.contains(current) {
            break;
        }
        // assert_eq!(events[index].event_type, EventType::Enter);
        index = if forward { index + 1 } else { index - 1 };
        loop {
            if events[index].token_type == *current {
                // assert_eq!(events[index].event_type, EventType::Exit);
                index = if forward { index + 1 } else { index - 1 };
                break;
            }
            index = if forward { index + 1 } else { index - 1 };
        }
    }
    index
}
 |