# Built-in
Combinations([1, 2, 3]);
# [ [  ], [ 1 ], [ 1, 2 ], [ 1, 2, 3 ], [ 1, 3 ], [ 2 ], [ 2, 3 ], [ 3 ] ]

# Note that it handles duplicates
Combinations([1, 2, 3, 1]);
# [ [  ], [ 1 ], [ 1, 1 ], [ 1, 1, 2 ], [ 1, 1, 2, 3 ], [ 1, 1, 3 ], [ 1, 2 ], [ 1, 2, 3 ], [ 1, 3 ],
#   [ 2 ], [ 2, 3 ], [ 3 ] ]