code: def _add_to_nested_dict(metrics):
      return {
          "": {
              "": metrics,
          },
      }
  
imports: import os
  import tensorflow
  from tensorflow_model_analysis import constants
  from tensorflow_model_analysis.eval_saved_model import testutil
  from tensorflow_model_analysis.proto import config_pb2
  from tensorflow_model_analysis.proto import metrics_for_slice_pb2
  from tensorflow_model_analysis.slicer.slicer_lib import OVERALL_SLICE_NAME
  from tensorflow_model_analysis.slicer.slicer_lib import SingleSliceSpec
  from tensorflow_model_analysis.view import util
  from tensorflow_model_analysis.view import view_types
  from google.protobuf import text_format
label_desc: Use image node_id 1 for calling a global function with example usage: _add_to_nested_dict(metrics) and returns: dict