More dictionary ops
Keys, values, items:
- d.keys() -> ["duck", "back"]
- d.values() -> ["duik", "rug"]
- d.items() -> [("duck","duik"), ("back","rug")]
Presence check:
- d.has_key("duck") -> 1; d.has_key("spam") -> 0
Values of any type; keys almost any
- {"name":"Guido", "age":43, ("hello","world"):1, 42:"yes", "flag": ["red","white","blue"]}