text: class ChallengeTitles {
    constructor() {
      this.knownTitles = [];
    }
    check(title) {
      if (typeof title !== 'string') {
        throw new Error(
          `Expected a valid string for ${title}, but got a(n) ${typeof title}`
        );
      }
      const titleToCheck = title.replace(/\s+/g, '').toLowerCase();
      if (titleToCheck.length === 0) {
        throw new Error('Expected a title length greater than 0');
      }
      const isKnown = this.knownTitles.includes(titleToCheck);
      if (isKnown) {
        throw new Error(`
      All challenges must have a unique title.
  
      The title ${title} is already assigned
      `);
      }
      this.knownTitles = [ ...this.knownTitles, titleToCheck ];
    }
  }
  
  module.exports = ChallengeTitles;
  