def clean_semver(cls, version_spec):
        return re.sub(r"([<>=~])\s+?v?", "\\1", version_spec, re.IGNORECASE)
def chart_title(self):
        """Returns a title for the chart."""
        if self.field:
            return 'Top filtered results for "{0:s}"'.format(self.field)
        return 'Top results for an unknown field after filtering'