protected function isNumericallyIndexedArray(array $phpArray): bool
    {
        foreach (array_keys($phpArray) as $key) {
            if (is_numeric($key) === false) {
                return false;
            }
        }
        return true;
    }
protected function isNumericallyIndexedArray(array $phpArray): bool
    {
        foreach (array_keys($phpArray) as $key) {
            if (is_numeric($key) === false) {
                return false;
            }
        }
        return true;
    }
protected function isNumericallyIndexedArray ( array $ phpArray ) : bool { foreach ( array_keys ( $ phpArray ) as $ key ) { if ( is_numeric ( $ key ) === false ) { return false ; } } return true ; }
Determine whether the given php array is a plain numerically indexed array

@param array $phpArray
@return boolean
Determine whether the given php array is a plain numerically indexed array