code: def env_string(name: str, required: bool=False, default: Union[Type[empty], str]=empty) -> str:
      
      value = get_env_value(name, default=default, required=required)
      if value is empty:
          value = ''
      return value
docs: Pulls an environment variable out of the environment returning it as a
      string. If not present in the environment and no default is specified, an
      empty string is returned.
  
      :param name: The name of the environment variable be pulled
      :type name: str
  
      :param required: Whether the environment variable is required. If ``True``
      and the variable is not present, a ``KeyError`` is raised.
      :type required: bool
  
      :param default: The value to return if the environment variable is not
      present. (Providing a default alongside setting ``required=True`` will raise
      a ``ValueError``)
      :type default: bool