Major Description
Right now R CMD check [1] interprets window.partitonBy and window.orderBy as S3 functions defined on the "partitionBy" class or "orderBy" class (similar to say summary.lm)
To avoid confusion I think we should just rename the functions and not use `.` in them ?
cc sunrui
[1] https://gist.github.com/shivaram/62866c4ca59c5d34b8963939cf04b5eb
