diff --git a/basic/demo_yield.py b/basic/demo_yield.py
new file mode 100644
index 0000000..24883e6
--- /dev/null
+++ b/basic/demo_yield.py
@@ -0,0 +1,39 @@
+def event():
+    print('start yield')
+    # return next(task) and yield next(task.send('set_two'))
+    one = yield 'get_one'
+    assert(one == 'set_two')
+    print(one)
+    yield 'get_two'  # return next(task) and yield next(task.send('set_two'))
+    print('exit yield')
+    yield  # yield next() to exit or raise StopIteration
+
+
+task = event()
+run_one = next(task)  # need next(task) init and next(task) == task.send(None)
+# so next(task) => yield 'get_one' => run_one = 'get_one'
+assert(run_one == 'get_one')
+run_two = task.send('set_two')
+assert(run_two == 'get_two')
+print('run : ', run_one, ' and ', run_two)
+
+try:
+    next(task)
+    print('run end')
+    next(task)  # will raise StopIteration
+except Exception as e:
+    print('yield StopIteration')
+
+if __name__ == '__main__':
+
+    def task():
+        while True:
+            print('hello')
+            yield
+
+    tmp = task()
+    while True:
+        next(tmp)
+
+    while True:
+        print('hello')
diff --git a/basic/demo_yield_task.py b/basic/demo_yield_task.py
new file mode 100644
index 0000000..d300dc5
--- /dev/null
+++ b/basic/demo_yield_task.py
@@ -0,0 +1,62 @@
+class Task:
+
+    def __init__(self, event=(lambda: print('task running'))):
+        self.event = event
+        self.cb = self.pre()
+        next(self.cb)
+        print('task init')
+
+    def pre(self):
+        print('task start')
+        flag = True
+        while flag is True:
+            flag = yield flag
+            self.event()
+        print('task exit')
+
+    def run(self, flag=True):
+        try:
+            res = self.cb.send(flag)
+            return res
+        except StopIteration as e:
+            return False
+
+
+if __name__ == "__main__":
+    tmp = Task()
+
+    assert(tmp.run())
+    assert(tmp.run())
+    assert(False == tmp.run(False))
+
+    print(tmp.run())
+    print(tmp.run(False))
+
+    class music:
+
+        def __init__(self):
+            self.task = Task(self.pre)
+            self.args = None
+            print('music init')
+
+        def pre(self):
+            print('pre ', self.args)
+
+        def play(self, size=10):
+            self.args = list(range(size))
+            print(self.task.run())
+
+        def stop(self):
+            print(self.task.run(False))
+            self.__init__()
+
+        def loop(self):
+            self.alive = False
+            while self.alive:
+                self.play()
+            stop()
+
+    tmp = music()
+    tmp.play()
+    tmp.stop()
+    tmp.play()