public async *fingerprints(tokens: string[]): AsyncIterableIterator<Fingerprint> {
    const hash = new RollingHash(this.k);
    let window: string[] = [];
    let filePos: number = -this.k;
    let bufferPos = 0;
    let minPos = 0;
    const buffer: number[] = new Array(this.windowSize).fill(Number.MAX_SAFE_INTEGER);
    for await (const [hashedToken, token] of this.hashTokens(tokens)) {
      filePos++;
      window = window.slice(-this.k + 1);
      window.push(token);
      if (filePos < 0) {
        hash.nextHash(hashedToken);
        continue;
      }
      // minPos define far right hashing.
      bufferPos = (bufferPos + 1) % this.windowSize;
      buffer[bufferPos] = hash.nextHash(hashedToken);
      if (minPos === bufferPos) {
        // Scan buffer starting from bufferPos for the far right minimal hashing.
        let i = (bufferPos + 1) % this.windowSize;
        for (; i !== bufferPos; i = (i + 1) % this.windowSize) {
          if (buffer[i] <= buffer[minPos]) {
            minPos = i;
          }
        }
        const offset = (minPos - bufferPos - this.windowSize) % this.windowSize;
        const start = filePos + offset;
      }
      else {
        if (buffer[bufferPos] <= buffer[minPos]) {
          minPos = bufferPos;
          const start = filePos + ((minPos - bufferPos - this.windowSize) % this.windowSize);
        }
       }
      yield {
         hash: buffer[minPos],
         start,
         stop: start + this.k - 1,
      };
    }
  }
}