Using generator expressions to directly create tuples is a not so good idea performance-wise. Use it only if you have memory issues because it is not very performant. Using tuple([list comprenension]) is at most twice as fast.

{"key1": "in the root namespace",
 "key2": "in the root namespace -- too",
 "tree1": {
     "key3": 32,
     "tree2": {
	 "key4": "get this as `tree1.tree2.key4'",
	 "key5": true,
	 "key6": "off"
     }
 }
}