replace(tag, value) {
    if (this.match(tag)) {
      this.add(value);
      this.position += length - 1;
      return true;
    }

    return false;
  }
@param {string|RegExp} tag  string to match in text
@param {value} value  string to replace tag with, if found at current position
@returns {boolean} true if the tag was processed, false otherwise