def _combine_accumulators(self, a, b):
    """Combines two accumulators.

    Args:
      a: A _LMomentsAccumulator.
      b: A _LMomentsAccumulator.

    Returns:
      A _LMomentsAccumulator computed as the combination of a and b.
    """
    # NaNs get preserved through division by a.count + b.count.
    a = _LMomentsAccumulator.make_nan_to_num(*a)
    b = _LMomentsAccumulator.make_nan_to_num(*b)

    # If one accumulator is empty return the other.
    if np.sum(a.count_l1) < np.sum(b.count_l1):
      a, b = b, a
    if np.sum(b.count_l1) == 0:
      return a

    a_count_l1, b_count_l1 = _pad_arrays_to_match(a.count_l1, b.count_l1)
    a_l1, b_l1 = _pad_arrays_to_match(a.l1, b.l1)
    a_count_l2, b_count_l2 = _pad_arrays_to_match(a.count_l2, b.count_l2)
    a_l2, b_l2 = _pad_arrays_to_match(a.l2, b.l2)
    a_count_l3, b_count_l3 = _pad_arrays_to_match(a.count_l3, b.count_l3)
    a_l3, b_l3 = _pad_arrays_to_match(a.l3, b.l3)
    a_count_l4, b_count_l4 = _pad_arrays_to_match(a.count_l4, b.count_l4)
    a_l4, b_l4 = _pad_arrays_to_match(a.l4, b.l4)

    combined_count_l1 = a_count_l1 + b_count_l1
    combined_count_l2 = a_count_l2 + b_count_l2
    combined_count_l3 = a_count_l3 + b_count_l3
    combined_count_l4 = a_count_l4 + b_count_l4

    combined_l1 = (a_l1 + np.true_divide(
        b_count_l1, combined_count_l1, where=combined_count_l1 > 0,
        out=np.zeros_like(a_l1)) * (b_l1 - a_l1))
    combined_l2 = (a_l2 + np.true_divide(
        b_count_l2, combined_count_l2, where=combined_count_l2 > 0,
        out=np.zeros_like(a_l2)) * (b_l2 - a_l2))
    combined_l3 = (a_l3 + np.true_divide(
        b_count_l3, combined_count_l3, where=combined_count_l3 > 0,
        out=np.zeros_like(a_l3)) * (b_l3 - a_l3))
    combined_l4 = (a_l4 + np.true_divide(
        b_count_l4, combined_count_l4, where=combined_count_l4 > 0,
        out=np.zeros_like(a_l4)) * (b_l4 - a_l4))

    return _LMomentsAccumulator(
        combined_count_l1, combined_count_l2, combined_count_l3,
        combined_count_l4, combined_l1, combined_l2, combined_l3, combined_l4)
Combines two accumulators.

    Args:
      a: A _LMomentsAccumulator.
      b: A _LMomentsAccumulator.

    Returns:
      A _LMomentsAccumulator computed as the combination of a and b.
    
tensorflow_transform/analyzers.py