def flatten_beam_dim(x):
  """Flattens the first two dimensions of a non-scalar array."""
  if x.ndim == 0:  # ignore scalars (e.g. cache index)
    return x
  return x.reshape((x.shape[0] * x.shape[1],) + x.shape[2:])
Flattens the first two dimensions of a non-scalar array.
language/gscan/xattn_model/model/decode.py