anchor.diff:      {A, B} = math_pos:make_same_length(A_, B_, Pos),
       A_plus_B = math_pos:plus(A, B, Base),
       ?equals(erlang:length(A_plus_B), erlang:length(A)),
  -    lists:all(fun(E) -> E >= 0 andalso E < Base end, A_plus_B) orelse
  -        ?ct_fail("math_pos:plus(A, B, ~B) evaluated to \"~.0p\" and contains invalid elements~n",
  -                 [Base, A_plus_B]).
  +    case lists:all(fun(E) -> E >= 0 andalso E < Base end, A_plus_B) of
  +        true -> true;
  +        _ -> ?ct_fail("math_pos:plus(A, B, ~B) evaluated to \"~.0p\" and "
  +                      "contains invalid elements~n",
  +                      [Base, A_plus_B])
  +    end.
   
   -spec prop_plus_valid1(A::[0..9], B::[0..9]) -> true.
   prop_plus_valid1(A_, B_) -> prop_plus_valid_base(A_, B_, front, 10).
  
positive.code:     {A, B} = math_pos:make_same_length(A_, B_, Pos),
      A_minus_B = math_pos:minus(A, B, Base),
      ?equals(erlang:length(A_minus_B), erlang:length(A)),
      lists:all(fun(E) -> E >= 0 andalso E < Base end, A_minus_B) orelse
          ?ct_fail("math_pos:minus(A, B, ~B) evaluated to \"~.0p\" and contains invalid elements~n",
                   [Base, A_minus_B]).
  
  -spec prop_minus_valid1(A::[0..9], B::[0..9]) -> true.
  prop_minus_valid1(A_, B_) -> prop_minus_valid_base(A_, B_, front, 10).
  
negative.code: prop_divide_valid_base(A, Div, Base) ->
      A_div = math_pos:divide(A, Div, Base),
      ?equals(erlang:length(A_div), erlang:length(A)),
      case lists:all(fun(E) -> E >= 0 andalso E < Base end, A_div) of
          true -> true;
          _ -> ?ct_fail("math_pos:divide(A, Div, ~B) evaluated to \"~.0p\" and "
                        "contains invalid elements~n",
                        [Base, A_div])
      end.
  
  -spec prop_divide_valid1(A::[0..9], Div::pos_integer()) -> true.
  prop_divide_valid1(A, Div) -> prop_divide_valid_base(A, Div, 10).
  