empty_list = []
list = [1,2,3,4,5]
length(list) #=> 5
[0 | list] #=> [0,1,2,3,4,5]
hd(list) #=> 1
tl(list) #=> [2,3,4,5]
Enum.at(list,3) #=> 4
list ++ [6,7] #=> [1,2,3,4,5,6,7]
list -- [4,2] #=> [1,3,5]