number_of_cases

result = []

for i in range(0,len(list_data)):
    for j in range(0,len(list_data)):
        index = ''
        index = str(list_data[i])+str(list_data[j])
        result.append(index)
for k in result:
    if (result.count(k) == 1):
        result = result
    else:
        result =  result.remove(k)
sorted_result = sorted(result)
result = sorted_result
# ==================================
return result
어디를 어떻게 수정해야하나요??