Revert "Remove _.isEmpty."
Revert "Remove _.isEmpty."

This reverts commit 717314911ce6f33b114b00c68d5103289a5f5ccd.

EverFi/chaplin,akre54/chaplin,mrb/chaplin,Everlane/chaplin,Everlane/chaplin,mrb/chaplin,cvd/chaplin,EverFi/chaplin,cvd/chaplin