协程greenlet类
from greenlet import greenlet
def work1():
for i in range(10):
print(f'--------work1------{i}')
g2.switch()
def work2():
for i in range(10):
print(f'--------work2------{i}')
g1.switch()
g1 = greenlet(work1)
g2 = greenlet(work2)
g1.switch() # 协程执行入口
g2.switch()