code: def load(obj, env=None, silent=True, key=None, filename=None):
      
      if yaml is None:  # pragma: no cover
          BaseLoader.warn_not_installed(obj, "yaml")
          return
  
      # Resolve the loaders
      # https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation
      # Possible values are `safe_load, full_load, unsafe_load, load`
      yaml_reader = getattr(yaml, obj.get("YAML_LOADER_FOR_DYNACONF"), yaml.load)
      if yaml_reader.__name__ == "unsafe_load":  # pragma: no cover
          warn(
              "yaml.unsafe_load is deprecated."
              " Please read https://msg.pyyaml.org/load for full details."
              " Try to use full_load or safe_load."
          )
  
      loader = BaseLoader(
          obj=obj,
          env=env,
          identifier="yaml",
          extensions=YAML_EXTENSIONS,
          file_reader=yaml_reader,
          string_reader=yaml_reader,
      )
      loader.load(filename=filename, key=key, silent=silent)
docs: Reads and loads in to "obj" a single key or all keys from source file.
  
      :param obj: the settings instance
      :param env: settings current env default='development'
      :param silent: if errors should raise
      :param key: if defined load a single key, else load all in env
      :param filename: Optional custom filename to load
      :return: None