message: mask len then should not be greater then inputs len. inputs len is either 2 or 3
diff: @@ -192,7 +192,7 @@ class BaseDenseAttention(Layer):
  raise ValueError(
  '{} layer mask must be a list, '
  'namely [query_mask, value_mask].'.format(class_name))
  - if len(mask) < 2 or len(mask) > 3:
  + if len(mask) < 2 or len(mask) > len(inputs):
  raise ValueError(
  '{} layer mask must be a list of length 2, namely [query_mask, '
  'value_mask]. Given length: {}'.format(class_name, len(mask)))
  