def __call__(self, num_update):
    'Return a new learning rate based on number of updates.\n\n        Parameters\n        ----------\n        num_update: nnvm Symbol\n            the number of updates applied to weight.\n        '
    raise NotImplementedError('__call__ method must be overridden.')
Return a new learning rate based on number of updates.

Parameters
----------
num_update: nnvm Symbol
    the number of updates applied to weight.
def __call__(self, num_update):
    'Return a new learning rate based on number of updates.\n\n        Parameters\n        ----------\n        num_update: nnvm Symbol\n            the number of updates applied to weight.\n        '
    raise NotImplementedError('__call__ method must be overridden.')