$youngPeopleDetails = $people
        ->where(function ($row) { return $row['age'] <= 50; })
        ->orderByAscending(function ($row) { return $row['firstName']; })
        ->thenByAscending(function ($row) { return $row['lastName']; })
        ->take(50)
        ->indexBy(function ($row) { return $row['phoneNumber']; })
        ->select(function ($row) { 
            return [
                'fullName'    => $row['firstName'] . ' ' . $row['lastName'],
                'address'     => $row['address'],
                'dateOfBirth' => $row['dateOfBirth'],
            ]; 
        });