message: fix element loci .toExpression for multi model structures,
diff: @@ -556,10 +556,7 @@ export namespace Loci {
  for (const e of loci.elements) {
  const { indices } = e;
  const { elements } = e.unit;
  -
  - const key = models.length === 1
  - ? e.unit.conformation.operator.name
  - : `${e.unit.conformation.operator.name} ${e.unit.model.label} ${e.unit.model.modelNum}`;
  + const key = e.unit.conformation.operator.name;
  let sourceIndices: UniqueArray<number, number>;
  if (sourceIndexMap.has(key)) sourceIndices = sourceIndexMap.get(key)!.xs;
  