my $hr1 = {};
my $hr2 = {};
my $hr3 = {"$hr1" => $hr1, "$hr2" => $hr2};
my @values = sort values %$hr3;
print "@values\n";
foreach my $v (sort values %$hr3) {
  print "$v\n";
  delete $hr3->{$values[1]};
  # some_function()
}