Return an operator_cloud

def get_operator_cloud(auth=None):
    '''
    Return an operator_cloud
    '''
    if auth is None:
        auth = __salt__['config.option']('keystone', {})
    if 'shade_opcloud' in __context__:
        if __context__['shade_opcloud'].auth == auth:
            return __context__['shade_opcloud']
    __context__['shade_opcloud'] = shade.operator_cloud(**auth)
    return __context__['shade_opcloud']