'Updates parameters according to the installed optimizer and the gradients computed
in the previous forward-backward batch.
Examples
>>> # An example of updating module parameters.
>>> mod.init_optimizer(kvstore=\'local\', optimizer=\'sgd\',
...     optimizer_params=((\'learning_rate\', 0.01), ))
>>> mod.backward()
>>> mod.update()
>>> print mod.get_params()[0][\'fc3_weight\'].asnumpy()
[[  5.86930104e-03   5.28078526e-03  -8.88729654e-03  -1.08308345e-03
6.13054074e-03   4.27560415e-03   1.53817423e-03   4.62131854e-03
4.69872449e-03  -2.42400169e-03   9.94111411e-04   1.12386420e-03'

def update(self):

    raise NotImplementedError()
