Decide how to implement the in lookup

[thedrow]

in is a reserved python keyword which means that I cannot use it as a function.
SQLAlchemy uses in_(). peewee uses the << operator.
IN() is also an option.
Currently it's in_values().

Let me know what you guys prefer.

[Gwildor]

Personally I would go with the << operator, simply because that will keep the code clean and you don't have to use another function. Although not everybody will get it directly, which is a big con. Perhaps the ^ operator makes more sense? Anyway, I think an operator is nicer to use than a function.