anchor.diff:  
   -export([encode/1,
            decode/1]).
  -
  -
  -%%============================================================================
  -%% Constants
  -%%============================================================================
   
   -define(BASE, 36).
   -define(TMIN, 1).
  
positive.code:   encode1(Rest, Output, H, B, N, Delta, Bias);
  encode1([], Output, H, _B, N, Delta, Bias) ->
    {Output, H, Delta + 1, N +1, Bias}.
  
  
  encode2(Rest, Output, H, B, N, Delta, Bias, Q, K) ->
    T = if
  
negative.code:           exit(overflow)
        end
    end.
  
  digit(C) when C >= $0, C =< $9 -> C - $0 + 26;
  digit(C) when C >= $A, C =< $Z -> C - $A;
  