Find the return value in a CIM response.

    The xmlns is needed because everything in CIM is a million levels
    of namespace indirection.

def _return_value(content, ns):
    """Find the return value in a CIM response.

    The xmlns is needed because everything in CIM is a million levels
    of namespace indirection.
    """
    doc = ElementTree.fromstring(content)
    query = './/{%(ns)s}%(item)s' % {'ns': ns, 'item': 'ReturnValue'}
    rv = doc.find(query)
    return int(rv.text)