Return the value for key from the environment or keyring.
        The keyring value is resolved from a local namespace or a global one.

def get(self, key, prompt_default='', prompt_help=''):
        """
        Return the value for key from the environment or keyring.
        The keyring value is resolved from a local namespace or a global one.
        """
        value = super(DjSecret, self).get(key, prompt_default, prompt_help='')
        if not value and self.raise_on_none:
            error_msg = "The %s setting is undefined in the environment and djset %s" % (key, self._glob)
            raise self.raise_on_none(error_msg)
        return value