import tensorflow as tf

def clip_tensor(t, length):
  """Clips the input tensor along the first dimension up to the length.

  Args:
    t: the input tensor, assuming the rank is at least 1.
    length: a tensor of shape [1]  or an integer, indicating the first dimension
      of the input tensor t after clipping, assuming length <= t.shape[0].

  Returns:
    clipped_t: the clipped tensor, whose first dimension is length. If the
      length is an integer, the first dimension of clipped_t is set to length
      statically.
  """
  clipped_t = tf.gather(t, tf.range(length))
  if not _is_tensor(length):
    clipped_t = _set_dim_0(clipped_t, length)
  return clipped_t


def pad_or_clip_tensor(t, length):
  """Pad or clip the input tensor along the first dimension.

  Args:
    t: the input tensor, assuming the rank is at least 1.
    length: a tensor of shape [1]  or an integer, indicating the first dimension
      of the input tensor t after processing.
