获取文本文件的第一行和最后一行的最有效方法是什么？

with open('file.txt', 'r') as file:
    first_line = file.readline().strip()
    last_line = None
    for line in file:
        last_line = line.strip()
    if last_line is not None:
        print("第一行:", first_line)
        print("最后一行:", last_line)
    else:
        print("文件为空")