/**
 * Classify whether a character code represents whitespace, punctuation, or
 * something else.
 *
 * Used for attention (emphasis, strong), whose sequences can open or close
 * based on the class of surrounding characters.
 *
 * Note that eof (`null`) is seen as whitespace.
 *
 * @param {Code} code
 * @returns {number|undefined}
 */
export function classifyCharacter(code: Code): number | undefined
export type Code = import('micromark-util-types').Code