src/Firebase.php
protected function buildUri($endpoint, $options = [])
    {
        if ($this->token !== '') {
            $options['auth'] = $this->token;
        }

        return $this->base.'/'.ltrim($endpoint, '/').'.json?'.http_build_query($options, '', '&');
    }
protected function buildUri($endpoint, $options = [])
    {
        if ($this->token !== '') {
            $options['auth'] = $this->token;
        }

        return $this->base.'/'.ltrim($endpoint, '/').'.json?'.http_build_query($options, '', '&');
    }
Create a standard uri based on the end point
and add the auth token.

@param string $endpoint The sub endpoint
@param array  $options  Extra options to be added

@return string