Clarifying the meaning of "weight"

[Saipraneet]

In the Intro notebook, the backward_pass_output from model.backward has a weight feature.
It seems to me that this is used for performing a weighted averaging in FedAvg, but this is not clear to me how. Perhaps this can be renamed to batch_size?

[jaehunro]

Valid point. Thanks for letting us know! I just merged #15 which renames weight in both BackwardPassOutput and ClientTrainerState to num_examples instead. We chose not to use batch_size because the definition is a bit too restrictive.