Use separate b_, e_ range members
Use separate b_, e_ range members

Summary: Use separate b_, e_ range members

Reviewed By: yfeldblum

Differential Revision: D23983016

fbshipit-source-id: b17061d7c1022c4776a8a8cb76ad5d0b9da9ace2

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly