def _get_num_slices(op_slice_sizes):
  """Returns the number of slices in a list of OpSlice sizes.

  Args:
    op_slice_sizes: List of list of slice sizes, where the outer list has a list
      per op and the inner list is the slice sizes of the op.

  Returns:
    Integer max number of slices in the list of ops.
  """
  return max([len(slices) for slices in op_slice_sizes])