sub out_iter_array {

   my $_aref = shift; my %_tmp; my $_order_id = 1;

   _croak("The argument to \"out_iter_array\" is not an array ref.")
      unless ( ref $_aref eq 'ARRAY' );

   return sub {
      my $_chunk_id = shift;

      if ( $_chunk_id == $_order_id && keys %_tmp == 0 ) {
         # already orderly
         $_order_id++; push @{ $_aref }, @_;
      }
      else {
         # hold temporarily otherwise until orderly
         @{ $_tmp{ $_chunk_id } } = @_;

         while ( 1 ) {
            last unless exists $_tmp{ $_order_id };
            push @{ $_aref }, @{ delete $_tmp{ $_order_id++ } };
         }
      }
   };
}