YAML and Booleans
# YAML.pm, YAML::Tiny
$VAR1 = {
          'bool false' => 'false',
          'bool true' => 'true'
        };
# YAML::Syck
$YAML::Syck::ImplicitTyping = 1;
$VAR1 = {
          'bool false' => '',
          'bool true' => 1
        };
# YAML::XS
$YAML::XS::Boolean = "JSON::PP"; # since v0.67
$VAR1 = {
          'bool false' => bless( do{\(my $o = 0)}, 'JSON::PP::Boolean' ),
          'bool true' => bless( do{\(my $o = 1)}, 'JSON::PP::Boolean' )
        };
# YAML::PP
my $ypp = YAML::PP::Loader->new(boolean => "JSON::PP");
$VAR1 = {
          'bool false' => bless( do{\(my $o = 0)}, 'JSON::PP::Boolean' ),
          'bool true' => bless( do{\(my $o = 1)}, 'JSON::PP::Boolean' )
        };