public function sendInvoice($assignmentId)
{
$assignment = Assignment::findorFail($assignmentId);
$user = $assignment->user;
Mail::send('email.invoiceToUser', ['booking_amount' => $assignment->booking_amount, 'completion_amount' => $assignment->completion_amount], function ($message) use($user) {
$message->to($user->email, $user->name)->subject('Invoice for assignment');
});
}
