merge()函数的两个参数均为已按相同规则排序的list类型数据：

def merge(arr1, arr2):
    result = []
    while arr1 and arr2:
        if arr1[0] < arr2[0]:
            result.append(arr1.pop(0))
        else:
            result.append(arr2.pop(0))
    if arr1:
        result += arr1
    if arr2:
        result += arr2
    return result