Reverses an array or a string.
reverse [ 0, 2, 4 ]
# --> sets f.ret to [ 4, 2, 0 ]
reverse "melimelo"
# --> sets f.ret to "olemilem"
Reverses f.ret if there are no arguments
[ 5, 6, 4 ] # sets f.ret to [ 5, 6, 4 ]
reverse _ # sets f.ret to [ 4, 6, 5 ]
Will fail if it finds nothing reversible.
shuffle, sort, and sort_by