docs: function median( out, arr, clbk ) {
  	var len = arr.length,
  		v, i;
  	for ( i = 0; i < len; i++ ) {
  		v = clbk( arr[ i ], i );
  		if ( typeof v === 'number' ) {
  			out[ i ] = MEDIAN( v );
  		} else {
  			out[ i ] = NaN;
  		}
  	}
  	return out;
  }