tkokof

local function try_get_upvalue(func, name)
    local upvalue_index = 1
    while true do
        local u_name, u_value = debug.getupvalue(func, upvalue_index)
        if not u_name then
            break
        elseif u_name == name then
            return u_name, u_value, upvalue_index
        end
        upvalue_index = upvalue_index + 1

tkokof

-- desc big int add & mul
-- maintainer hugoyu

local big_int = {}

local min_add_digit_num = 9
local min_mul_digit_num = 5

local function digit_num(v)
    return #tostring(v)