for my $k (@required_fields) {
  my $v = $href->{$k};
  StripLTSpace($v);
  $v or return DIRTY $row, "ERROR: required field $k not present";
}

##</code><code>##

for my $k (@required_fields) {
  for my $v ($href->{$k}) {
    StripLTSpace($v);
    $v or return DIRTY $row, "ERROR: required field $k not present";
  }
}

##</code><code>##

for my $k (@required_fields) {
  my $vr = \$href->{$k};
  StripLTSpace($$vr);
  $$vr or return DIRTY $row, "ERROR: required field $k not present";
}