add yield.md 2

Author: wb-dy589354

docs/03_链表/yild.md

@@ -151,4 +151,29 @@ producer(consumer())
 整个流程无锁，由一个线程执行，produce和consumer协作完成任务，所以称为“协程”，
 而非线程的抢占式多任务。
 """
+```
+```py
+# -*- coding:utf-8 -*-
+import time
+def consumer():
+    r = '342'
+    while True:
+        n = yield r
+        if not n:
+            return
+        print('[CONSUMER] Consuming %s...' % n)
+        time.sleep(1)
+        r = '200 OK'
+def produce(c):
+    print '## ',c.next()
+    n = 0
+    while n < 5:
+        n = n + 1
+        print('[PRODUCER] Producing %s...' % n)
+        r = c.send(n)
+        print('[PRODUCER] Consumer return: %s' % r)
+    c.close()
+if __name__=='__main__':
+    c = consumer()
+    produce(c)
 ```