def isNonPairTag(self, isnonpair=None):
        """
        True if element is listed in nonpair tag table (``br`` for example) or
        if it ends with ``/>`` (``<hr />`` for example).

        You can also change state from pair to nonpair if you use this as
        setter.

        Args:
            isnonpair (bool, default None): If set, internal nonpair state is
                      changed.

        Returns:
            book: True if tag is nonpair.
        """
        if isnonpair is None:
            return self._isnonpairtag

        if not self._istag:
            return

        if isnonpair:
            self.endtag = None
            self.childs = []

        self._isnonpairtag = isnonpair
True if element is listed in nonpair tag table (``br`` for example) or
        if it ends with ``/>`` (``<hr />`` for example).

        You can also change state from pair to nonpair if you use this as
        setter.

        Args:
            isnonpair (bool, default None): If set, internal nonpair state is
                      changed.

        Returns:
            book: True if tag is nonpair.