Things got out of hand messing with a simple Leet Code problem

add_two.go

type ListNode struct {
  Val int
  Next *ListNode
 }

func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
	pc := make(chan int, 4)

	var (
		wg   sync.WaitGroup
		root *ListNode
	)

	// producer
	// Send the Link List values to the channel alternating
	wg.Add(1)
	go func(wg *sync.WaitGroup) {
		defer wg.Done()
		for l1 != nil || l2 != nil {
			if l1 != nil {
				pc <- l1.Val
				l1 = l1.Next
			} else {
				pc <- 0
			}
			if l2 != nil {
				pc <- l2.Val
				l2 = l2.Next
			} else {
				pc <- 0
			}
		}
		close(pc)
	}(&wg)

	// Consumer
	wg.Add(1)
	go func(wg *sync.WaitGroup) {
		defer wg.Done()
		var (
			a, b, sum, carry int
			ok               bool
			current          *ListNode
		)

		for {
			// recieve from producer in pairs
			a = <-pc
			b, ok = <-pc

			if !ok {
				if carry > 0 {
					current.Next = &ListNode{Val: carry}
				}
				break
			}

			// Do the maths
			sum = a + b + carry
			carry = 0
			if sum > 9 {
				carry = 1
				sum -= 10
			}

			if root == nil {
				root = &ListNode{}
				current = root
			} else {
				current.Next = &ListNode{}
				current = current.Next
			}
			current.Val = sum
		}
	}(&wg)

	wg.Wait()
	return root
}