# First array
# This array could contain any number of items
my @firstArray = ( "item1", "item2", "item3" );

##</code><code>##

# Results array
my @results = (
  [ "item1" ],
  [ "item2" ],
  [ "item3" ],
  [ "item1", "item2" ],
  [ "item1", "item3" ],
  [ "item2", "item3" ],
  [ "item1", "item2", "item3" ]
);
# Note: [ "item1", "item2" ] & [ "item2", "item1" ]
# should be considered as the same.