def func():
    print(‘第一次‘)
    yield 1
    print(‘第二次‘)
    yield 2
    print(‘第三次‘)
    yield 3
    print(‘第四次‘)

g=func()
print(g)
# 生成器就是迭代器
g.__iter__()

# g.__next__()会触发函数体代码的运行，然后遇到yield停下来，将yield后的值
# 当做本次调用的结果返回

res1=g.__next__()
print(res1)


res2=g.__next__()
print(res2)

res3=g.__next__()
print(res3)

res4=g.__next__()


len(‘aaa‘) # ‘aaa‘.__len__()

next(g)    # g.__next__()
iter(可迭代对象)     # 可迭代对象.__iter__()

def my_range(start,stop,step=1):
    print(‘start...‘)
    while start < stop:
        yield start
        start+=step
    print(‘end....‘)


g=my_range(1,5,2) 
print(next(g))	# start...
				# 1
print(next(g))	# 3
print(next(g))	# end....
				# StopIteration

for n in my_range(1,7,2):
    print(n)
# start...
# 1
# 3
# 5
# end....