Wrapper around _batching_scheme with hparams.

def hparams_to_batching_scheme(hparams,
                               drop_long_sequences=False,
                               shard_multiplier=1,
                               length_multiplier=1):
  """Wrapper around _batching_scheme with hparams."""
  return batching_scheme(
      batch_size=hparams.batch_size,
      min_length=hparams.min_length,
      max_length=hparams.max_length,
      min_length_bucket=hparams.min_length_bucket,
      length_bucket_step=hparams.length_bucket_step,
      drop_long_sequences=drop_long_sequences,
      shard_multiplier=shard_multiplier,
      length_multiplier=length_multiplier)