code: function set(property, value, defaultValue) {
      if (value === undefined) {
        if (defaultValue === undefined) {
          defaultValue = this.keys[property];
        }
        if (typeof defaultValue === 'function') {
          this[property] = defaultValue.call(this);
        } else {
          this[property] = defaultValue;
        }
      } else {
        this[property] = value;
      }
    }
docs: Sets a property on the configuration object, allowing for a
  default value
  @api private