code: def _add_default_dims(self, idx, dimensions):
      dim_names = [dim.name for dim in dimensions]
      if idx is None:
          if "Level" not in dim_names:
              dimensions.append(Dimension("Level", "Error"))
      else:
          if "ModelName" not in dim_names:
              dimensions.append(Dimension("ModelName", self.model_name))
          if "Level" not in dim_names:
              dimensions.append(Dimension("Level", "Model"))
      return dimensions
  
imports: import abc
  import os
  import ts.metrics.metric_cache_errors
  from ts.metrics.dimension import Dimension
  from ts.metrics.metric_abstract import MetricAbstract
  from ts.metrics.metric_type_enum import MetricTypes
label_desc: Use image node_id 2 for calling the MetricCacheAbstract obj's underlying member method code with example usage: obj._add_default_dims(idx, dimensions) and returns: dimensions