var a1 = [1, 2, 3, "abc"]
val a2 = series(4..10)
val a3 = a1 ~ a2

writeln "initial values ..."
writeln "a1: ", a1
writeln "a2: ", a2
writeln "a3: ", a3
writeln()

a1[4] = a2[4]
writeln "after setting a1[4] = a2[4] ..."
writeln "a1: ", a1
writeln "a2: ", a2
writeln "a3: ", a3
writeln()

writeln "a2[1]: ", a2[1]
writeln()

writeln "using index alternate ..."
writeln "a2[5; 0]: ", a2[5; 0]
writeln "a2[10; 0]: ", a2[10; 0]
writeln()