php - Guzzle argument with [] fail to recognize as array -

in example of oficial documentation of guzzle:

$request = $client->createrequest('put', 'http://httpbin.org/put', ['body' => 'testing...']);

but:

"argument 3 passed guzzlehttp\client::request() must of type array, string given"

php version: php 5.5.9-1ubuntu4.9 (cli)

is version of php or code lack of something?

looks argument 3 must array try

$request = $client->createrequest('put', 'http://httpbin.org/put', array('body' => 'testing...'));

Alconcel