Booleans have two possible values. Are there types that have three possible values? [duplicate]

Answer 1

1. At least one language has this: C#: int? num = null;, now num is actually Nullable (the question mark is a "syntactic sugar") see: http://msdn.microsoft.com/en-us/library/1t3y8s4s%28v=vs.80%29.aspx and http://en.wikipedia.org/wiki/Nullable_type
2. Don't know Python, but it depends on your preference: usability (enum or class) vs. efficiency (4 bit fields)