add python threading examples and intros for lec 18 spoc discuss

related_info/lab7/semaphore_condition/thr-ex4.py

@@ -0,0 +1,13 @@
+import threading  
+  
+class MyThread(threading.Thread):  
+    def __init__(self):  
+        threading.Thread.__init__(self)  
+      
+    def run(self):  
+        print "I am %s" % (self.name)  
+      
+if __name__ == "__main__":  
+    for i in range(0, 5):  
+        my_thread = MyThread()  
+        my_thread.start()