[1 2 3]:a; # numeric only array, assigned to a and then dropped
10,:a; # assign to a [0 1 2 3 4 5 6 7 8 9]
a 0= puts # pick element at index 0 (stack: 0)
a 10+puts # append 10 to the end of a
10 a+puts # prepend 10 to a