Type error with lr_scheduler

[zyfhaha]

After several epochs running, an error will raise as following:

/hfta/optim/lr_scheduler.py", line 247, in _update_lr
    res = this_lr * multiplier
TypeError: unsupported operand type(s) for *: 'Coefficient' and 'float'

it seems that the type of this_lr is 'Coefficient' and it can not do * with 'float'

[zyfhaha]

It seems that there is something wrong with 'step size'. if I set '[5]', the error will appear at the end of 5th epoch.