`Reader#scan`

[rapodaca]

Keep taking as long as the closure keeps returning Some. Useful for reading element symbols, and other information from molfiles.

Follows the method of the same name in this.

pub fn scan<T>(
    &mut self
    cb: impl Fn(&Vec<Character>) -> Option<Action<T>>,
) -> Result<Option<T>, Error> {
    // as in article
}