code: def _update_variable_collection(collection_name, vars_to_add):
      """Add variables to collection."""
      collection = {}
      for var in v1.get_collection(collection_name):
          collection[_hashable_var_key(var)] = var
      # Skip variables that are in the collection already: O(n) runtime.
      for var_ref in vars_to_add:
          if var_ref in collection:
              continue
          v1.add_to_collection(collection_name, vars_to_add[var_ref])
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from distutils.version import LooseVersion
  import tensorflow.compat.v1
  import tensorflow.compat.v2
  from tensorflow.python import tf2
  from tensorflow.python.keras.metrics import Metric
  from tensorflow.python.tpu import tpu_function
  from tensorflow_estimator.python.estimator.head import regression_head
label_desc: Use image node_id 7 for calling a global function with example usage: _update_variable_collection(collection_name, vars_to_add) without return types