day7.py

results = {"b": 956}

queue = a.split("\n")

while queue:
	test = queue.pop(0)
	(operation, resultant) = test.split(" -> ")
	spaces = operation.count(" ")
	print test
	process=True
	if spaces == 0:
		op = "SET"
		arg1 = operation
		try:
			arg1 = int(arg1)
		except:
			try:
				arg1 = results[arg1]
			except:
				process = False		
	elif spaces == 1:
		(op , arg1) = operation.split(" ")
		try:
			arg1 = int(arg1)
		except:
			try:
				arg1 = results[arg1]
			except:
				process = False
	elif spaces == 2:
		(arg1, op, arg2) = operation.split(" ")
		try:
			arg1 = int(arg1)
		except:
			try:
				arg1 = results[arg1]
			except:
				print "fail"
				process = False
		try:
			arg2 = int(arg2)
		except:
			try:
				arg2 = results[arg2]
			except:
				print "fail"
				process = False	
	if not process:
		queue.append(test)
		continue
	if resultant == "b":
		continue
	if op == "SET":
		results[resultant] = arg1
	elif op == "AND":
		results[resultant] = arg1 & arg2
	elif op == "LSHIFT":
		results[resultant] = arg1 << arg2
	elif op == "RSHIFT":
		results[resultant] = arg1 >> arg2
	elif op == "NOT":
		results[resultant] = ~ arg1 
	elif op == "OR":
		results[resultant] = arg1 | arg2

print results["a"]