anchor.diff:  
   find(_,_) -> erlang:nif_error(undef).
   
  -
  +%% Shadowed by erl_bif_types: maps:from_list/1
   -spec from_list(List) -> Map when
       List :: [{Key,Value}],
       Key :: term(),
  
positive.code: from_list(_) -> erlang:nif_error(undef).
  
  
  -spec is_key(Key,Map) -> boolean() when
      Key :: term(),
      Map :: map().
  
negative.code: new() -> erlang:nif_error(undef).
  
  
  %% Shadowed by erl_bif_types: maps:put/3
  -spec put(Key,Value,Map1) -> Map2 when
      Key :: term(),
      Value :: term(),
  