列表中很多重复的元素

我正在尝试创建一个在列表中找到最重复元素的函数。我想遍历列表，检查每个元素的计数并进行比较（使用2个变量numnum和numnum2）

出了点问题，它总是打印6。

l1 = [1, 5, 7, 7, 7, 7, 7, 7, 7, 7, 1, 3, 6, 6, 3, 4, 2, 6]

print(l1)


def mostrepeating(list1=None):
    if list1 is None:
        print('No list was received in the function.')
    else:
        numnum, numnum2, result = 0, 0, 0
        for num in list1:
            if list1.index(num) == 0:
                numnum = list1.count(num)
                result = num
            else:
                numnum2 = list1.count(num)
                if numnum2 > numnum:
                    result = num
                    numnum = numnum2
        print(result)


mostrepeating(l1)

问题来源：stackoverflow