isine example: actually play some tones

the thread in the background actually needs time to do something
sensible. this is most easily achieved by simply sleeping in the
foreground thread.

i addition to the 440 Hz tone, also play 1 kHz, to demonstrate how
the change() function is used.

isine.py

@@ -7,6 +7,7 @@
 from __future__ import print_function
 
 import sys
+import time
 from threading import Thread
 from multiprocessing import Queue
 
@@ -87,6 +88,7 @@ class SinePlayer(Thread):
 isine = SinePlayer()
 isine.start()
 
-def change(f):
-    isine.change(f)
-    
+time.sleep(1)
+isine.change(1000)
+time.sleep(1)
+