How to use the ngx-custom-validators.CustomValidators.rangeLength function in ngx-custom-validators

func: CustomValidators.notEqual,
      params: ["notEqual"]
    },
    notEqualTo: {
      func: CustomValidators.notEqualTo,
      params: ["notEqualTo"]
    },
    number: {
      func: CustomValidators.number
    },
    range: {
      func: CustomValidators.range,
      params: ["range"]
    },
    rangeLength: {
      func: CustomValidators.rangeLength,
      params: ["rangeLength"]
    },
    url: {
      func: CustomValidators.url
    },
    uuid: {
      func: CustomValidators.uuid
    }
  };

  addValidator(key: string, validator: NarikValidator) {
    this._validators[key] = validator;
  }

  validators() {
    return this._validators;