sub recursive {
    my( $state, $arg ) = @_;
    ...
    if( ( $arg = $state->{ $arg } ) == ... ) {
         return recursive( $state, $arg );
    }
    else {
         return 0;
    }
}

sub rec_helper{
    my $arg = shift;
    my %state;
    return recursive( \%state, $arg );
}