code: def _get_env_list(obj, env):
      
      # add the [default] env
      env_list = [obj.get("DEFAULT_ENV_FOR_DYNACONF")]
      # compatibility with older versions that still uses [dynaconf] as
      # [default] env
      global_env = obj.get("ENVVAR_PREFIX_FOR_DYNACONF") or "DYNACONF"
      if global_env not in env_list:
          env_list.append(global_env)
      # add the current env
      if obj.current_env and obj.current_env not in env_list:
          env_list.append(obj.current_env)
      # add a manually set env
      if env and env not in env_list:
          env_list.append(env)
      # add the [global] env
      env_list.append("GLOBAL")
      return [env.lower() for env in env_list]
docs: Creates the list of environments to read
  
      :param obj: the settings instance
      :param env: settings env default='DYNACONF'
      :return: a list of working environments