def _find(value: str, target: str, pos: int) -> int:
    """Find the *target* in *value* after *pos*.

    Returns the *value* length if *target* isn't found.
    """
    try:
        return value.index(target, pos)
    except ValueError:
        return len(value)
Find the *target* in *value* after *pos*.

    Returns the *value* length if *target* isn't found.
    
src/werkzeug/routing/rules.py