anchor.diff:     , 'cons' => fun ?MODULE:cons/2
      , 'append' => fun erlang:'++'/2
      , 'reverse' => fun lists:reverse/1
  -   , 'car' => fun ?MODULE:car/1
  -   , 'cdr' => fun ?MODULE:cdr/1
  +   , 'car' => fun erlang:hd/1
  +   , 'cdr' => fun erlang:tl/1
      , 'caar' => fun ?MODULE:caar/1
      , 'cadr' => fun ?MODULE:cadr/1
      , 'cddr' => fun ?MODULE:cddr/1
  
positive.code:         ]).
  
  %% Base Library functions implemented in this module
  -export([ car/1
          , caar/1
          , cadr/1
          , caddr/1
          , cdr/1
          , cddr/1
          , cdddr/1
          , cons/2
  
negative.code: 
  'cons'(X, Y) -> [X | Y].
  
  'caar'([[X | _] | _]) ->
    X.
  
  