WP_HTTP_IXR_Client::query

	 *              to the function signature.
	 *
	 * @return bool
	 */
	public function query( ...$args ) {
		$method  = array_shift( $args );
		$request = new IXR_Request( $method, $args );
		$xml     = $request->getXml();

		$port = $this->port ? ":$this->port" : '';
		$url  = $this->scheme . '://' . $this->server . $port . $this->path;
		$args = array(
			'headers'    => array( 'Content-Type' => 'text/xml' ),
			'user-agent' => $this->useragent,
			'body'       => $xml,
		);

		// Merge Custom headers ala #8145.
		foreach ( $this->headers as $header => $value ) {
			$args['headers'][ $header ] = $value;
		}

		/**
		 * Filters the headers collection to be sent to the XML-RPC server.
		 *
		 * @since 4.4.0
		 *
		 * @param string[] $headers Associative array of headers to be sent.
		 */
		$args['headers'] = apply_filters( 'wp_http_ixr_client_headers', $args['headers'] );

		if ( false !== $this->timeout ) {
			$args['timeout'] = $this->timeout;
		}

		// Now send the request.
		if ( $this->debug ) {
			echo '<pre class="ixr_request">' . htmlspecialchars( $xml ) . "\n</pre>\n\n";
		}

		$response = wp_remote_post( $url, $args );

		if ( is_wp_error( $response ) ) {
			$errno       = $response->get_error_code();
			$errorstr    = $response->get_error_message();
			$this->error = new IXR_Error( -32300, "transport error: $errno $errorstr" );
			return false;
		}

		if ( 200 != wp_remote_retrieve_response_code( $response ) ) {
			$this->error = new IXR_Error( -32301, 'transport error - HTTP status code was not 200 (' . wp_remote_retrieve_response_code( $response ) . ')' );
			return false;
		}

		if ( $this->debug ) {
			echo '<pre class="ixr_response">' . htmlspecialchars( wp_remote_retrieve_body( $response ) ) . "\n</pre>\n\n";
		}

		// Now parse what we've got back.
		$this->message = new IXR_Message( wp_remote_retrieve_body( $response ) );
		if ( ! $this->message->parse() ) {
			// XML error.
			$this->error = new IXR_Error( -32700, 'parse error. not well formed' );
			return false;
		}

		// Is the message a fault?
		if ( 'fault' === $this->message->messageType ) {
			$this->error = new IXR_Error( $this->message->faultCode, $this->message->faultString );
			return false;
		}