scan
abstract fun scan(tokens: TokensCache, iterator: TokensCache.Iterator, delimiters: MutableList<DelimiterParser.Info>): Int
Finds all tokens that open or close element represented by this parser. Invoked by EmphasisLikeParser.collectDelimiters.
Delimiters matching will be handled by the EmphasisLikeParser.balanceDelimiters after delimiters from all parsers will be collected.
Return
Number of steps to advance token iterator.