OPEN_CLOSE_REGEXES
val OPEN_CLOSE_REGEXES: List<<Error class: unknown class><<Error class: unknown class>, <Error class: unknown class>?>>
see {@link http://spec.commonmark.org/0.21/#html-blocks}
nulls mean "Next line should be blank"
see {@link http://spec.commonmark.org/0.21/#html-blocks}
nulls mean "Next line should be blank"