/** * @import {Options, State} from 'mdast-util-to-markdown' */ /** * @param {State} state * @returns {Exclude} */ export function checkRule(state) { const marker = state.options.rule || '*' if (marker !== '*' && marker !== '-' && marker !== '_') { throw new Error( 'Cannot serialize rules with `' + marker + '` for `options.rule`, expected `*`, `-`, or `_`' ) } return marker }