You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: Solution.go
    path of file: ./repos/awesome-golang-algorithm/leetcode/1001-1100/1071.Greatest-Common-Divisor-of-Strings
    
    the code of the file until where you have to start completion: package Solution

func Solution(str1 string, str2 string) string {
	ls1, ls2 := len(str1), len(str2)
	common := make([]int, 0)
	for i := 1; i <= ls1 && i <= ls2; i++ {
		if ls1%i == 0 && ls2%i == 0 {
			common = append(common, i)
		}
	}
	var check func(int) bool
	check = func(windowSize int) bool {
		target := str1[:windowSize]
		start := windowSize
		for ; start <= ls1-windowSize; start += windowSize {
			end := start + windowSize
			if str1[start:end] != target {
				
    
func Solution(str1 string, str2 string) string {
	ls1, ls2 := len(str1), len(str2)
	common := make([]int, 0)
	for i := 1; i <= ls1 && i <= ls2; i++ {
		if ls1%i == 0 && ls2%i == 0 {
			common = append(common, i)
		}
	}
	var check func(int) bool
	check = func(windowSize int) bool {
		target := str1[:windowSize]
		start := windowSize
		for ; start <= ls1-windowSize; start += windowSize {
			end := start + windowSize
			if str1[start:end] != target {
				return false
			}
		}
		target1 := str2[:windowSize]
		if target1 != target {
			return false
		}
		start = windowSize
		for ; start <= ls2-windowSize; start += windowSize {
			end := start + windowSize
			if str2[start:end] != target1 {
				return false
			}
		}
		return true
	}
	for i := len(common) - 1; i >= 0; i-- {
		windowSize := common[i]
		if check(windowSize) {
			return str1[:windowSize]
		}
	}
	return ""
}