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let array = [ 13 11 7 5 3 2 ]
array.[ 1 .. 3 ] # [ 13 11 7 ]
array.[ 1 .. ] # [ 13 11 7 5 3 2 ]
array.[ .. 3 ] # [ 13 11 7 ]
array.[ .. ] # [ 13 11 7 5 3 2 ]
# TODO: for .. do
1 + 2 # 3
(+) 1 2 3 # 6
1 - 2 # -1