def start(listen_address=None):
"""Starts a chat session and enables logging to output to the console
listen_address must be tuple of the form ('127.0.0.1', 9091). If the specified
address isn't available the chat session will not be started.
"""
global chat
atexit.register(quiet_stop)
if not chat:
if listen_address:
chat = Chat(listen_address)
else:
chat = Chat()
elif listen_address:
print "Warning: chat already started"
return
chat.enableConsoleLogging()
try:
chat.start()
except:
chat = None
raise
