public function testExchangeYCanRetrieveFunds()
 {
     $exchangeX = new Example\Exchange(new Example\ExchangeYGateway());
     $this->assertEquals(-58.98, $exchangeX->retrieveFunds());
 }
<?php

require 'exchanges.php';
use DesignPatterns\Gateway\Example\Exchanges as Example;
$exchangeX = new Example\Exchange(new Example\ExchangeXGateway());
$exchangeX->placeBet(array('market_id' => 11239, 'selection_id' => 2, 'price' => 3.1, 'size' => 35, 'type' => 'B'));
$lastBet = $exchangeX->retrieveLastBet();
echo 'The market id of last bet in ExchangeX is ' . $lastBet['market_id'] . "\n";
echo 'Funds in ExchangeX: ' . $exchangeX->retrieveFunds() . "\n";
$exchangeY = new Example\Exchange(new Example\ExchangeYGateway());
$exchangeY->placeBet(array('market_id' => 1982, 'selection_id' => 6, 'price' => 3.0, 'size' => 10, 'type' => 'L'));
$lastBet = $exchangeY->retrieveLastBet();
echo 'The market id of last bet in ExchangeY is ' . $lastBet['market_id'] . "\n";
echo 'Funds in ExchangeY: ' . $exchangeY->retrieveFunds();