adding chapter 7 source code

Chapter7/multithreading/thread1-extra.py

@@ -0,0 +1,27 @@
+# thread1-extra.py to create simple threads with function (using threads list to simplly the code)
+
+import threading
+from threading import Thread as Thread
+from time import sleep
+
+def print_hello():
+    sleep(2)
+    print("{}: Hello".format(threading.current_thread().name))
+
+def print_message(msg):
+    sleep(1)
+    print("{}: {}".format(threading.current_thread().name, msg))
+
+threads = []
+# creating threads
+threads.append(Thread(target=print_hello, name="Th 1"))
+threads.append(Thread(target=print_hello, name="Th 2"))
+threads.append(Thread(target=print_message, args=["Good morning"], name="Th 3"))
+
+# start the threads
+for th in threads:
+    th.start()
+
+# wait till all are done
+for th in threads:
+    th.join()