use 5.012; # strict, //
use warnings;
use JSON 4.0;
use Data::Dumper;

print "JSON::VERSION = $JSON::VERSION\n";

my $json = JSON->new;
$json->boolean_values(0,1);


test@BruceDEV:~$ perl Perl-Testing/JSON-boolean_values.pl
JSON::VERSION = 4.02

Can't locate object method "boolean_values" via package "JSON" at Perl-Testing/JSON-boolean_values.pl line 11.