Escape "@" in Guzzle body values

gistfile1.php

<?php

// Fix: cURL/Guzzle body parameters may not start with @, see: https://bugs.php.net/bug.php?id=50060
foreach ($body as $key => $value) {
    if (is_string($value) && substr($value, 0, 1) == '@') {
        $body[$key] = ' ' . $value;
    }
}