code: function which(hashstr) {
    if (typeof hashstr !== 'string' || hashstr === '') {
      throw new TypeError('The hashstr param must be an non-empty string.');
    }
    const fields = hashstr.split('$');
  
    if (fields.length < 3 || fields[0] !== '') {
      throw new TypeError(
        'The hashstr param provided is not in a supported format.'
      );
    }
    const idf = fields[1];
  
    if (queue.length === 0) {
      throw new Error('No algorithm installed.');
    }
  
    for (const name of queue) {
      if (funcs[name].identifiers().indexOf(idf) === -1) continue;
      return name;
    }
    return null;
  }
docs: Returns the name of the algorithm that has generated the hash string.
  @public
  @param {string} hashstr Secure hash string generated from this package.
  @return {string|null} The name of password hashing algorithm.