sub new
{
    my $class = shift;
    my $self = bless {}, $class;
    return $self->init(@_);
}


sub init
{
    my $self = shift;
    $self->_alloc_pstate;

    my %arg = @_;
    my $api_version = delete $arg{api_version} || (@_ ? 3 : 2);
    if ($api_version >= 4) {
        require Carp;
...