UNIVERSAL->import deprecated 

use UNIVERSAL qw( isa );                 # deprecated - warns

if( isa($thing, 'ARRAY') ) {

if( UNIVERSAL::isa($thing, 'ARRAY') ) {  # Frowned upon

if( $thing->isa('ARRAY') ) {             # Fails on unblessed ref

if( ref($thing) eq 'ARRAY' or eval { $thing->isa('ARRAY') } ) {