Merge new file into old

def merge(self, n):
        """Merge new file into old
        """
        if os.path.isfile(n[:-4]):
            old = Utils().read_file(n[:-4]).splitlines()
        if os.path.isfile(n):
            new = Utils().read_file(n).splitlines()
        with open(n[:-4], "w") as out:
            for l1, l2 in itertools.izip_longest(old, new):
                if l1 is None:
                    l1 = ""
                if l2 is None:
                    l2 = ""
                if l1 != l2:
                    out.write(l2 + "\n")
                else:
                    out.write(l1 + "\n")
            print("The file {0} merged in file {1}".format(
                n.split("/")[-1], n[:-4].split("/")[-1]))