【入门夯实】do语句块：显式的局部作用域分组

local function calc()
    local tmp = 0
    tmp = tmp + 100
    -- 200 行之后 tmp 已经不用了，但名字还占着
    local tmp2 = tmp * 2
    return tmp2
end
print(calc())

local function calc()
    local result = 0
    do
        local rate = 2
        result = 100 * rate
    end
    do
        local rate = 3
        result = result + 50 * rate
    end
    return result
end
print(calc())

do
    local material = "黑铁矿石"
    print("本次锻造消耗：" .. material)
end
print("锻造完成")