// input. If there are multiple such BiasAdds, one is returned (with no
// guarantee as to which one). If there are no BiasAdds that use the output,
// returns a null BiasAddOp.
BiasAddOp GetBiasAdd(Value op) {
  for (auto &use : op.getUses()) {
    auto bias_add = dyn_cast_or_null<BiasAddOp>(use.getOwner());
    // If it's a BiasAdd, check that the conv op is the first input.