> coffee power_set.coffee
POWER SET of
[]
POWER SET of 4,2,1
[]
[ 1 ]
[ 2 ]
[ 2, 1 ]
[ 4 ]
[ 4, 1 ]
[ 4, 2 ]
[ 4, 2, 1 ]
POWER SET of dog,c,b,a
[]
[ 'a' ]
[ 'b' ]
[ 'b', 'a' ]
[ 'c' ]
[ 'c', 'a' ]
[ 'c', 'b' ]
[ 'c', 'b', 'a' ]
[ 'dog' ]
[ 'dog', 'a' ]
[ 'dog', 'b' ]
[ 'dog', 'b', 'a' ]
[ 'dog', 'c' ]
[ 'dog', 'c', 'a' ]
[ 'dog', 'c', 'b' ]
[ 'dog', 'c', 'b', 'a' ]