Macaroon.add_first_party_caveat

You're seeing just the function add_first_party_caveat, go back to Macaroon module for more information.
Link to this function

add_first_party_caveat(macaroon, predicate)

Specs

add_first_party_caveat(Macaroon.Types.Macaroon.t(), binary()) ::
  Macaroon.Types.Macaroon.t()

Add a first-party caveat to a Macaroon provided a predicate