caselessRemove example

$standardPorts = ['http' => 80, 'https' => 443];
                    $scheme = $changes['uri']->getScheme();
                    if (isset($standardPorts[$scheme]) && $port != $standardPorts[$scheme]) {
                        $changes['set_headers']['Host'] .= ':'.$port;
                    }
                }
            }
            $uri = $changes['uri'];
        }

        if (!empty($changes['remove_headers'])) {
            $headers = self::caselessRemove($changes['remove_headers'], $headers);
        }

        if (!empty($changes['set_headers'])) {
            $headers = self::caselessRemove(array_keys($changes['set_headers']), $headers);
            $headers = $changes['set_headers'] + $headers;
        }

        if (isset($changes['query'])) {
            $uri = $uri->withQuery($changes['query']);
        }

        

if (isset($options['form_params'])) {
            if (isset($options['multipart'])) {
                throw new InvalidArgumentException('You cannot use '
                    .'form_params and multipart at the same time. Use the '
                    .'form_params option if you want to send application/'
                    .'x-www-form-urlencoded requests, and the multipart '
                    .'option to send multipart/form-data requests.');
            }
            $options['body'] = \http_build_query($options['form_params'], '', '&');
            unset($options['form_params']);
            // Ensure that we don't have the header in different case and set the new value.             $options['_conditional'] = Psr7\Utils::caselessRemove(['Content-Type'], $options['_conditional']);
            $options['_conditional']['Content-Type'] = 'application/x-www-form-urlencoded';
        }

        if (isset($options['multipart'])) {
            $options['body'] = new Psr7\MultipartStream($options['multipart']);
            unset($options['multipart']);
        }

        if (isset($options['json'])) {
            $options['body'] = Utils::jsonEncode($options['json']);
            unset($options['json']);