my %SWITCH = (
   CAT      => 0b00001,
   DOG      => 0b00010,
   HAMSTER  => 0b00100,
   FERRIT   => 0b01000,
   FISH     => 0b10000);
   
my $petInput = 2;
my @PETS;

for (keys %SWITCH) {
    if ($petInput & $SWITCH{$_}){push (@PETS, $_);}        
}

foreach (@PETS){print $_."\n";}