docs: def merge_dict(base, additional):
      """
      Combine two dictionary-like objects.
  
      Notes
      -----
      Code from https://github.com/pypa/warehouse
      Copyright 2013 Donald Stufft
  
      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.
      """
      if base is None:
          return additional
  
      if additional is None:
          return base
  
      if not (
          isinstance(base, collections.Mapping)
          and isinstance(additional, collections.Mapping)
      ):
          return additional
  
      merged = base
      for key, value in additional.items():
          if isinstance(value, collections.Mapping):
              merged[key] = merge_dict(merged.get(key), value)
          else:
              merged[key] = value
  
      return merged