utils/root.js
function reduceVal(conf, val) {
  val = val.call(conf);
  return typeof val === 'function' ? reduceVal(conf, val) : val;
}
function reduceVal(conf, val) {
  val = val.call(conf);
  return typeof val === 'function' ? reduceVal(conf, val) : val;
}
function reduceVal ( conf , val ) { val = val . call ( conf ) ; return typeof val === 'function' ? reduceVal ( conf , val ) : val ; }
Call function `val` in context of `conf`
@param {Object} conf
@param {Function} val
Call function val in context of conf