anchor.diff:  -export([new/1, is_element/2]).
   -include("merge_index.hrl").
   
  +-ifdef(TEST).
  +-ifdef(EQC).
  +-include_lib("eqc/include/eqc.hrl").
  +-endif.
  +-include_lib("eunit/include/eunit.hrl").
  +-endif.
  +
   %% These settings give us a max 256 keys with 0.05 error rate.
   -define(M, 1600).
   -define(K, 4).
  
positive.code:     Xi = (X+Y) rem ?M,
      Yi = (Y+I) rem ?M,
      calc_idxs(I-1, Xi, Yi, [Xi | Acc]).
  
negative.code:     Gap = NextOnPos - Pos - 1,
      case Gap > 0 of
          true ->
              Bits = <<0:Gap/integer, 1:1/integer>>,
              [Bits|generate_bits(Pos + Gap + 1, T)];
          false ->
              Bits = <<1:1/integer>>,
              [Bits|generate_bits(Pos + 1, T)]
      end;
  generate_bits(Pos, []) ->
      Gap = ?M - Pos,
      [<<0:Gap/integer>>].
  