'Given a value from an environment variable this splits it up
into small chunks depending on the defined envvar list splitter.
If the splitter is set to `None`, which means that whitespace splits,
then leading and trailing whitespace is ignored.  Otherwise, leading
and trailing splitters usually lead to empty items being included.'

def split_envvar_value(self, rv):

    return (rv or '').split(self.envvar_list_splitter)
