old_contents: # Copyright The PyTorch Lightning team.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  """Helper functions to operate on metric values. """
  import numbers
  from typing import Any
  
  import torch
  
  from pytorch_lightning.utilities.apply_func import apply_to_collection
  from pytorch_lightning.utilities.exceptions import MisconfigurationException
  
  
  def metrics_to_scalars(metrics: Any) -> Any:
      """
      Recursively walk through a collection and convert single-item tensors to scalar values
  
      Raises:
          MisconfigurationException:
              If ``value`` contains multiple elements, hence preventing conversion to ``float``
      """
  
      def to_item(value: torch.Tensor) -> numbers.Number:
          if value.numel() != 1:
              raise MisconfigurationException(
                  f"The metric `{value}` does not contain a single element" f" thus it cannot be converted to float."
              )
          return value.item()
  
      return apply_to_collection(metrics, torch.Tensor, to_item)
  
new_contents: # Copyright The PyTorch Lightning team.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  """Helper functions to operate on metric values. """
  import numbers
  from typing import Any
  
  import torch
  
  from pytorch_lightning.utilities.apply_func import apply_to_collection
  from pytorch_lightning.utilities.exceptions import MisconfigurationException
  
  
  def metrics_to_scalars(metrics: Any) -> Any:
      """
      Recursively walk through a collection and convert single-item tensors to scalar values
  
      Raises:
          MisconfigurationException:
              If tensors inside ``metrics`` contains multiple elements, hence preventing conversion to a scalar.
      """
  
      def to_item(value: torch.Tensor) -> numbers.Number:
          if value.numel() != 1:
              raise MisconfigurationException(
                  f"The metric `{value}` does not contain a single element, thus it cannot be converted to a scalar."
              )
          return value.item()
  
      return apply_to_collection(metrics, torch.Tensor, to_item)
  
subject: Fix comments for metrics_to_scalars (#8782)