function getFoldOnLine(cm, line) {
        var pos = CodeMirror.Pos(line, 0);
        var folds = cm.findMarksAt(pos) || [];
        folds = folds.filter(isFold);
        return folds.length ? folds[0] : undefined;
    }
Helper function to return the fold text marker on a line in an editor
@param   {CodeMirror} cm   The CodeMirror instance for the active editor
@param   {Number}     line The line number representing the position of the fold marker
@returns {TextMarker} A CodeMirror TextMarker object