<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def firmware_version(self):
 """ Returns firmware version. Args: None Returns: Dictionary Raises: None """

        namespace = "urn:brocade.com:mgmt:brocade-firmware-ext"

        request_ver = ET.Element("show-firmware-version", xmlns=namespace)

        ver = self._callback(request_ver, handler='get')
        return ver.find('.//*{%s}os-version' % namespace).text