def __repr__(self):
        return "<Requirement(package={package}, version='{version}')>".format(
            package=self.package, version=self.version)
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'