'123.45' * * @param Collection $accounts * @param Carbon $start * @param Carbon $end * * @return array */ public function spentPerMonth(Collection $accounts, Carbon $start, Carbon $end); /** * Returns an array of the amount of money spent in the given accounts (on withdrawals, opening balances and transfers) * grouped by month like so: "2015-01" => '123.45' * * @param Collection $accounts * @param Carbon $start * @param Carbon $end * * @return array */ public function earnedPerMonth(Collection $accounts, Carbon $start, Carbon $end); }