Tri boolean handling yes, no and doesn't exist with the AWS Lambda session object attributes and Alexa Endpoint

yes_no_with_attribs_ask.py

'''
(Python)
Using yes and no (intents) worked very well for me.
I enjoy coding for yes and no intents.  
I found that users enjoy the experience and understand it intuitively.

The below variables derive from:

...
attributes_in = session['attributes'] <-- if session.get('attributes') <-- session obj
attributes_in = {} <-- if not session.get('attributes') <-- session obj
...
intent_name <- request['intent']['name'] <-- event['request'] <-- event obj

'''


#...  	Start keeping track of happiness.  
#	If they are already happy, keep going.
elif intent_name == "AMAZON.YesIntent":
		cur_attributes_in = attributes_in
		if not cur_attributes_in.get('userIsHappy'):
			cur_attributes_in.update({'userIsHappy': True})
			return doSomethingCoolFunc(request, cur_attributes_in)
		else:
			return doSomethingCoolFunc(request, cur_attributes_in)


	
#...  If they are unhappy once, try again.  
#     If they were never happy or became unhappy twice, exit gracefully.
elif intent_name == "AMAZON.NoIntent":
		cur_attributes_in = attributes_in	
		if cur_attributes_in.get('userIsHappy') != None:
			if cur_attributes_in.get('userIsHappy') == False:
				return do_graceful_stop({},{})
			else:
				cur_attributes_in.update({'userIsHappy': False})
				return trySomethingElseFunc(request, cur_attributes_in)
		else:
			return do_graceful_stop({},{})