String representation. kwargs are passed to `pprint.pformat`.

        Args:
            verbose: Verbosity level
            title: Title string.

def to_string(self, verbose=0, title=None, **kwargs):
        """
        String representation. kwargs are passed to `pprint.pformat`.

        Args:
            verbose: Verbosity level
            title: Title string.
        """
        from pprint import pformat
        s = pformat(self, **kwargs)
        if title is not None:
            return "\n".join([marquee(title, mark="="), s])
        return s