lib/util.js
function partial(fn) {
  var preset=_slice.call(arguments, 1), self=this
  return function(){ return fn.apply(self, arrfill(preset, arguments)) }
}
function partial(fn) {
  var preset=_slice.call(arguments, 1), self=this
  return function(){ return fn.apply(self, arrfill(preset, arguments)) }
}
function partial ( fn ) { var preset = _slice . call ( arguments , 1 ) , self = this return function ( ) { return fn . apply ( self , arrfill ( preset , arguments ) ) } }
allows out-of-order arguments by using `undefined`
allows out - of - order arguments by using undefined