def build_attrs(self, base_attrs, extra_attrs=None):
        """
        Bootstrap integration adds form-control to the classes of the widget.
        This works only for "plain" input-based widgets however. In addition,
        we need to add a custom class "babybuddy-tags-editor" for the javascript
        file to detect the widget and take control of its contents.
        """
        attrs = super().build_attrs(base_attrs, extra_attrs)
        class_string = attrs.get("class", "")
        class_string = class_string.replace("form-control", "")
        attrs["class"] = class_string + " babybuddy-tags-editor"
        return attrs

        Bootstrap integration adds form-control to the classes of the widget.
        This works only for "plain" input-based widgets however. In addition,
        we need to add a custom class "babybuddy-tags-editor" for the javascript
        file to detect the widget and take control of its contents.
        
core/widgets.py