Method update

src/ability.js:45–53

(rules)

  }

  update(rules) {
    if (Array.isArray(rules)) {
      this.emit('update', { rules, ability: this });
      this[PRIVATE_FIELD].originalRules = Object.freeze(rules.slice(0));
      this[PRIVATE_FIELD].rules = this.buildIndexFor(this.rules);
    }

    return this;
  }

  buildIndexFor(rules) {
    const indexedRules = {};