Method flatten

packages/core/src/utils/Utils.ts:890–892

(arrays: T[][], deep?: boolean)

  }

  static flatten<T>(arrays: T[][], deep?: boolean): T[] {
    return arrays.flatMap(v => (deep && Array.isArray(v) ? this.flatten(v as unknown as T[][], true) : v));
  }

  static isOperator(key: PropertyKey, includeGroupOperators = true): boolean {
    if (!includeGroupOperators) {