docs: def update_from(
              self,
              obj=None,
              yaml_env=None,
              yaml_file=None,
              json_env=None,
              json_file=None,
              env_namespace=None,
              ):
          """
          Update dict from several sources at once.
  
          This is simply a convenience method that can be used as an alternative
          to making several calls to the various
          :meth:`~ConfigLoader.update_from_*` methods.
  
          Updates will be applied in the order that the parameters are listed
          below, with each source taking precedence over those before it.
  
          :arg obj: Object or name of object, e.g. 'myapp.settings'.
          :arg yaml_env: Name of an environment variable containing the path to
              a YAML config file.
          :arg yaml_file: Path to a YAML config file, or a file-like object.
          :arg json_env: Name of an environment variable containing the path to
              a JSON config file.
          :arg json_file: Path to a JSON config file, or a file-like object.
          :arg env_namespace: Common prefix of the environment variables
              containing the desired config.
          """
          if obj:
              self.update_from_object(obj)
          if yaml_env:
              self.update_from_yaml_env(yaml_env)
          if yaml_file:
              self.update_from_yaml_file(yaml_file)
          if json_env:
              self.update_from_json_env(json_env)
          if json_file:
              self.update_from_json_file(json_file)
          if env_namespace:
              self.update_from_env_namespace(env_namespace)