Shallow table copy in Lua 4

I'm making a mod for an old video game that uses Lua 4, and I need a way to create a shallow copy of an inputted table. I found this routine on the web:

http://lua-users.org/wiki/CopyTable

function shallowcopy(orig)
    local orig_type = type(orig)
    local copy
    if orig_type == 'table' then
        copy = {}
        for orig_key, orig_value in pairs(orig) do
            copy[orig_key] = orig_value
        end
    else -- number, string, boolean, etc
        copy = orig
    end
    return copy
end

However, the routine was written for a later version of Lua. For instance, the pairs function does not exist in Lua 4. Also, the function is not recursive. How would I write an equivalent routine that works in Lua 4 and is recursive? Thanks!

[edit]

Updated post.

Lua 4 has a for loop for tables.

The table for statement traverses all pairs (index,value) of a given table. It has the following syntax:

   stat ::= for name `,' name in exp1 do block end

Refer to the Lua 4 reference manual section 4.4.4

https://www.lua.org/manual/4.0/manual.html#4.4

A shallow copy routine does not need to be recursive. This would only affect table values which are copied by reference and hence have all their members on-board.