def get_vm_cpu_rate(self, uuid):    """    get cpu rate    100 * diff_vm_cpu_time / (diff_sys_cpu_time * 1 * 1e9)    return cpurate%    """    result = 0    vm_info = self.vms_info.get(uuid, None)    vm_info_before = self.vms_info_before.get(uuid, None)    if not vm_info or not vm_info_before:        return result    info = vm_info.get("cpu_mem_state_info", None)    info_before = vm_info_before.get("cpu_mem_state_info", None)    cpu_time = info[-1]    cpu_time_before = info_before[-1]    last = self.vms_info_timestamp    before = self.vms_info_before_timestamp    if cpu_time and cpu_time_before:        result = 100 * abs(cpu_time_before - cpu_time) / \                (abs(last - before) * 1 * 1e9)    return round(result, 2)