Function valBefore

dash/dash-renderer/src/actions/dependencies.js:157–157

 * Provide a value known to be before or after v, according to idValSort
 */
const valBefore = v => (isNumeric(v) ? v - 1 : 0);
const valAfter = v => (typeof v === 'string' ? v + 'z' : 'z');

function addMap(depMap, id, prop, dependency) {