function convertSlotToVal(theirSlot, iface = undefined) {
    const slot = reverseSlot(theirSlot);

    if (slot[1] === '+') {
      importExportTables.hasExport(slot) || Fail`Unknown export ${slot}`;
      return importExportTables.getExport(slot);
    }
    if (!importExportTables.hasImport(slot)) {
      if (iface === undefined) {
        iface = `Alleged: Presence ${ourId} ${slot}`;
      }
      const { val, settler } = importExportTables.makeValueForSlot(slot, iface);
      if (importHook) {
        importHook(val, slot);
      }
      if (slot[0] === 'p') {
        // A new promise
        settlers.set(slot, settler);
      }
      importExportTables.markAsImported(slot, val);
      valToSlot.set(val, slot);
    }

    // If we imported this slot, mark it as one our peer exported.
    recvSlot.add(slot);
    return importExportTables.getImport(slot);
  }
Set up import

@type {import('@endo/marshal').ConvertSlotToVal<CapTPSlot>}