In the README.md the line:
pipefy.allCards("821643", filter='{field: "updated_at", operator: gt, value: 2018-08-01T23:50:11-03:00}')
Should read:
pipefy.allCards(pipe_id, filter='{field: "updated_at", operator: gt, value: "2018-08-01T23:50:11-03:00"}')