markLines(n: number): this {
    if (n < 1) {
      return this;
    }
    this.hasSegment = false;
    if (this.pos + n >= this.buffer.length) {
      this._realloc();
    }
    while (n--) {
      this.buffer[this.pos++] = SEMICOLON;
    }
    return this;
  }
Adds `n` markers for generated lines to the mappings.