When handling proof chains, the dataset must be temporarily extended with a number of quads that constitute the "previous" proof. This function calculates those extra quads.
the array of Proofs in chain order
current index into allProofs
Optional
the possible anchor that includes the proof reference triple
proof
When handling proof chains, the dataset must be temporarily extended with a number of quads that constitute the "previous" proof. This function calculates those extra quads.