'get learning rate for index.
Parameters
index : int
The index for weight
Returns
lr : float
learning rate for this index'

def _get_lr(self, index):

    mom = 0.0
    if (self.lr_scheduler is not None):
        (lr, mom) = self.lr_scheduler(self.num_update)
    else:
        lr = self.lr
    if (index in self.lr_mult):
        lr *= self.lr_mult[index]
    elif (index in self.idx2name):
        lr *= self.lr_mult.get(self.idx2name[index], 1.0)
    return (lr, mom)
