fs(f, s) = map(f, s)
f1(x) = 2x
f2(x) = x^2
fsf1(s) = fs(f1, s)
fsf2(s) = fs(f2, s)

s1 = [0, 1, 2 ,3]
s2 = [2, 4, 6, 8]
println("fsf1 of s1 is $(fsf1(s1))")
println("fsf2 of s1 is $(fsf2(s1))")
println("fsf1 of s2 is $(fsf1(s2))")
println("fsf2 of s2 is $(fsf2(s2))")