Function hasCustomToString

src/from.ts:95–98

* Check if object has a custom toString() (not Object.prototype.toString).

(obj: object)

 * Check if object has a custom toString() (not Object.prototype.toString).
 */
function hasCustomToString(obj: object): boolean {
  const toString = (obj as { toString?: unknown }).toString;
  return typeof toString === 'function' && toString !== Object.prototype.toString;
}

/**
 * Check if object has Symbol.toPrimitive.