code: function normalizeOptions(options = {}) {
      const hasGroups = options.groups && options.groups.length > 0;
      const groups = hasGroups ? options.groups : DEFAULT_GROUPS;
      const allowSamePrecedence = options.allowSamePrecedence !== false;
  
      return {
          groups,
          allowSamePrecedence
      };
  }
docs: Normalizes options.
  
  @param {Object|undefined} options - A options object to normalize.
  @returns {Object} Normalized option object.