docs: function (label) {
                  var boundaryRegex = this.boundaryRegex;
                  var boundaries = [0]; // mandatory 0 to check the start of the label
                  while (boundaryRegex.exec(label) !== null) {
                      boundaries.push(boundaryRegex.lastIndex);
                  }
                  boundaryRegex.lastIndex = 0;
                  return boundaries;
              }