@Override
  public IntermediateLayer visitExpression(
      Expression expression, IntermediateLayerVisitorContext context) {
    throw new UnsupportedOperationException(
        "Unsupported statement type: " + expression.getClass().getName());
  }
Responsible for constructing {@link IntermediateLayer} through Expression.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/expression/visitor/IntermediateLayerVisitor.java