public function createMerchant(
        $email_address = null,
        $merchant = null,
        $bank_account_href = null,
        $name = null,
        $meta = null)
    {
        $params = array(
            'email_address' => $email_address,
            'name' => $name,
            'meta' => $meta,
        );
        if($merchant) {
            $params = array_merge($params, $merchant);
        }
        $customer = $this->customers->create();
        if($bank_account_href) {
            $bank_account = BankAccount::get($bank_account_href);
            $bank_account->associateToCustomer($customer);
        }
        return $customer;
    }