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local function get_env()
    local env = setmetatable({}, { __index = getfenv() })

    local i = 1
    while true do
        local k, v = debug.getlocal(2, i)
        if not k then
            break
        end
        env[k] = v
        i = i + 1
    end

    return env
end

local function pack(...)
    return { n = select("#", ...), ... }
end

local function unpack(args, i)
    i = i or 1
    if i > args.n then return end
    return args[i], unpack(args, i + 1)
end

local function foo(a, b, to_eval)
    local some_local = 4

    -- your function script ends here

    local env = get_env()

    local success, chunk_or_error = pcall(loadstring, to_eval)
    if not success then
        print("compilation_error: ", chunk_or_error)
        return
    end

    local packed = pack(pcall(setfenv(chunk_or_error, env)))

    local success = packed[1]

    if not success then
        local runtime_error = packed[2]
        print("runtime_error: ", runtime_error)
        return
    end
    return unpack(packed, 2)
end

local to_eval = [[
    a = a + 1
    print(a + b + some_local)
    return 2, 4
]]
print(foo(2, 3, to_eval))