Return textual data of UK extremes.
        
        request:
            metoffer.CAPABILITIES            Returns available extreme date
                                             and issue time
            metoffer.LATEST                  Returns data of latest extremes
                                             for all regions

def text_uk_extremes(self, request):
        """
        Return textual data of UK extremes.
        
        request:
            metoffer.CAPABILITIES            Returns available extreme date
                                             and issue time
            metoffer.LATEST                  Returns data of latest extremes
                                             for all regions
        """
        return json.loads(self._query(TEXT, OBSERVATIONS, UK_EXTREMES, request, "").decode(errors="replace"))