def drops.of
import ezx@1.11.0.0/src/lock/up.bend as Upimport Base
import ezx@1.11.0.0/src/ledger/upgrade.bend as U
1138# every committed tree that moved, removed
1139def drops.of(ss: List<&2, U.Swap>) -> List<&2, String>:
1140 match ss:
1141 case []:
1142 []
1143 case U.Swap{old, _new} <> t:
1144 old <> drops.of(t)