Modification of the example code

To illustrate the fact that we can share code seemlessly with different
scheduling behavior, at ease with futurist. Moreover, the example code
shows how the concurrency/parallel execution can be observed from same
code, just by changing the executor. This demonstrates the power of
futurist interfaces.

Change-Id: Ifdd2a89c8cd9d06f54900960a69debc41b42ab3d

doc/source/examples.rst

@@ -8,24 +8,67 @@ Creating and using a synchronous executor
 
 .. testcode::
 
-    import time
+    # NOTE: enable printing timestamp for additional data
 
+    import sys
     import futurist
+    import eventlet
 
     def delayed_func():
-        time.sleep(0.1)
-        return "hello"
+        print("started")
+        eventlet.sleep(3)
+        print("done")
 
+    #print(datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
     e = futurist.SynchronousExecutor()
     fut = e.submit(delayed_func)
-    print(fut.result())
+    eventlet.sleep(1)
+    print("Hello")
+    eventlet.sleep(1)
     e.shutdown()
+    #print(datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
 
 **Expected output:**
 
 .. testoutput::
 
-    hello
+    started
+    done
+    Hello
+
+------------------------------------------------
+Creating and using a green thread-based executor
+------------------------------------------------
+
+.. testcode::
+
+    # NOTE: enable printing timestamp for additional data
+
+    import sys
+    import futurist
+    import eventlet
+
+    def delayed_func():
+        print("started")
+        eventlet.sleep(3)
+        print("done")
+
+    #print(datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
+    e = futurist.GreenThreadPoolExecutor()
+    fut = e.submit(delayed_func)
+    eventlet.sleep(1)
+    print("Hello")
+    eventlet.sleep(1)
+    e.shutdown()
+    #print(datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S"))
+
+**Expected output:**
+
+.. testoutput::
+
+    started
+    Hello
+    done
 
 
 ------------------------------------------
@@ -53,32 +96,6 @@ Creating and using a thread-based executor
 
     hello
 
-------------------------------------------------
-Creating and using a green thread-based executor
-------------------------------------------------
-
-.. testcode::
-
-    import time
-
-    import futurist
-
-    def delayed_func():
-        time.sleep(0.1)
-        return "hello"
-
-    e = futurist.GreenThreadPoolExecutor()
-    fut = e.submit(delayed_func)
-    print(fut.result())
-    e.shutdown()
-
-**Expected output:**
-
-.. testoutput::
-
-    hello
-
-
 -------------------------------------------
 Creating and using a process-based executor
 -------------------------------------------