16. 【选修】解决方案：迭代器和生成器

练习解决方案：实现 my_enumerate

lessons = ["Why Python Programming", "Data Types and Operators", "Control Flow", "Functions", "Scripting"]

def my_enumerate(iterable, start=0):
    count = start
    for element in iterable:
        yield count, element
        count += 1

for i, lesson in my_enumerate(lessons, 1):
    print("Lesson {}: {}".format(i, lesson))

输出：

Lesson 1: Why Python Programming
Lesson 2: Data Types and Operators
Lesson 3: Control Flow
Lesson 4: Functions
Lesson 5: Scripting

练习解决方案：Chunker

以下是一种实现方式。你可以在此 Stack Overflow 页面上找到该实现。

def chunker(iterable, size):
    """Yield successive chunks from iterable of length size."""
    for i in range(0, len(iterable), size):
        yield iterable[i:i + size]

for chunk in chunker(range(25), 4):
    print(list(chunk))

输出：

[0, 1, 2, 3]
[4, 5, 6, 7]
[8, 9, 10, 11]
[12, 13, 14, 15]
[16, 17, 18, 19]
[20, 21, 22, 23]
[24]

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