编辑代码

function sum(a, b, c) {
    return a + b + c
}

function curry() {
    // TODO
}

const freeSum = curry(sum)

// test case
console.log(freeSum(1, 2, 3))
console.log(freeSum(1, 2)(3))
console.log(freeSum(1)(2, 3))
console.log(freeSum(1)(2)(3))