sub _test_mode {
  my $self = shift;
  use Scalar::Util 'reftype';
  my $tkey = '_'.__PACKAGE__.'_TEST_MODE';
  if(reftype($self) eq 'HASH'){
    if(defined $self->{$tkey}){
      return 1;
    }
    else{
      $self->{$tkey} = 1;
    }
  }
  elsif(reftype($self) eq 'ARRAY'){
    if($self->[-1] eq $tkey){
      return 1;
    }
    else{
      push @{$self},$tkey;
    }
  }
}