local function search(haystack, needle)
    local indices = {}
    for i = 1, #haystack do
        if haystack[i] == needle then indices:insert(i) end
    end
    local c = #indices
    if c == 0 then error("Needle not found in haystack.") end
    local t = (c == 1) ? "time" : "times"
    print($"The needle occurs {c} {t} in the haystack.")
    if #indices == 1 then
        print($"It occurs at index {indices[1]}")
    else
       print($"It first occurs at index {indices[1]}")
       print($"It last  occurs at index {indices:back()}")
    end
    print()
end

local haystack = {"Zig", "Zag", "Wally", "Ronald", "Bush", "Krusty", "Charlie", "Bush", "Boz", "Zag"}
print($"The haystack is: \n{haystack:concat(", ")}\n")
local needles = {"Wally", "Bush", "Zag", "George"}
for needles as needle do
    print($"The needle is {needle}.")
    search(haystack, needle)
end