Stripe\HttpClient\CurlClient::encode PHP Method

    public static function encode($arr, $prefix = null)
    {
        if (!is_array($arr)) {
            return $arr;
        }
        $r = array();
        foreach ($arr as $k => $v) {
            if (is_null($v)) {
                continue;
            }
            if ($prefix) {
                if ($k !== null && (!is_int($k) || is_array($v))) {
                    $k = $prefix . "[" . $k . "]";
                } else {
                    $k = $prefix . "[]";
                }
            }
            if (is_array($v)) {
                $enc = self::encode($v, $k);
                if ($enc) {
                    $r[] = $enc;
                }
            } else {
                $r[] = urlencode($k) . "=" . urlencode($v);
            }
        }
        return implode("&", $r);
    }

 public function testEncode()
 {
     $a = array('my' => 'value', 'that' => array('your' => 'example'), 'bar' => 1, 'baz' => null);
     $enc = CurlClient::encode($a);
     $this->assertSame('my=value&that%5Byour%5D=example&bar=1', $enc);
     $a = array('that' => array('your' => 'example', 'foo' => null));
     $enc = CurlClient::encode($a);
     $this->assertSame('that%5Byour%5D=example', $enc);
     $a = array('that' => 'example', 'foo' => array('bar', 'baz'));
     $enc = CurlClient::encode($a);
     $this->assertSame('that=example&foo%5B%5D=bar&foo%5B%5D=baz', $enc);
     $a = array('my' => 'value', 'that' => array('your' => array('cheese', 'whiz', null)), 'bar' => 1, 'baz' => null);
     $enc = CurlClient::encode($a);
     $expected = 'my=value&that%5Byour%5D%5B%5D=cheese' . '&that%5Byour%5D%5B%5D=whiz&bar=1';
     $this->assertSame($expected, $enc);
     // Ignores an empty array
     $enc = CurlClient::encode(array('foo' => array(), 'bar' => 'baz'));
     $expected = 'bar=baz';
     $this->assertSame($expected, $enc);
 }