def qvalue(self):
        """The qvalue, or priority, of this value."""
        val = self.params.get('q', '1')
        if isinstance(val, HeaderElement):
            val = val.value
        try:
            return float(val)
        except ValueError as val_err:
            """Fail client requests with invalid quality value.

            Ref: https://github.com/cherrypy/cherrypy/issues/1370
            """
            raise cherrypy.HTTPError(
                400,
                'Malformed HTTP header: `{}`'.format(str(self)),
            ) from val_err
The qvalue, or priority, of this value.
cherrypy/lib/httputil.py