How to use the ipyleaflet.CircleMarker function in ipyleaflet

except GPXXMLSyntaxException:
            return None
        pts = [p.point for p in trace.get_points_data()]
        bbox = trace.get_bounds()
        mins = (bbox.min_latitude, bbox.min_longitude)
        maxs = (bbox.max_latitude, bbox.max_longitude)
        bbox = mins, maxs
        center = list(bbox_center(*bbox))
        z = zoom_for_bbox(*(mins + maxs))
        m = ipyleaflet.Map(center=center, zoom=z + 1)
        # FIXME: make path styling configurable
        poly = ipyleaflet.Polyline(locations=[(p.latitude, p.longitude)
            for p in pts], fill=False)
        m.add_layer(layer=poly)
        for p in pts:
            cm = ipyleaflet.CircleMarker(location=(p.latitude, p.longitude), radius=5)
            m.add_layer(layer=cm)
        self.data = m
        return m

for i,k in enumerate(keyValues):
                if i > 0:
                    key += "."
                if k in value:
                    key += value[k]
                
            keys.append(key)

            if key in self._markers:
                marker = self._markers[key]
            else:
                if self._icon != None:
                    icon = maps.Icon(icon_url=self._icon,icon_size=[40,30])
                    marker = maps.Marker(icon=icon)
                else:
                    marker = maps.CircleMarker()
                    marker.stroke = border
                    marker.fill_opacity = opacity

                self._map.add_layer(marker)
                self._markers[key] = marker
                if len(popup) > 0:
                    marker.popup = widgets.HTML()

            if self._lat in value and self._lon in value:
                lat = value[self._lat]
                lon = value[self._lon]
                marker.location = (lat,lon)

            if tracking and center == None:
                center = marker.location