code: public static function isIndexSet(array& $data, string $key): bool
      {
          try {
              self::getArrayItemByPointSeparatedKey($data, $key);
              return true;
          } catch (Exception $e) {
              return false;
          }
      }
docs: The method checks if the input tree contains an element with the specified
  index (the index contains a point-separator of tiers)
  @param mixed[] $data Input tree.
  @param string $key The field name. The name of the nested field is formed by
  the path of the tree the tiers of which are separated by the point.
  @return boolean