anchor.diff:  bif_return_type(is_binary, [_], _) -> bool;
   bif_return_type(is_float, [_], _) -> bool;
   bif_return_type(is_function, [_], _) -> bool;
  +bif_return_type(is_function, [_,_], _) -> bool;
   bif_return_type(is_integer, [_], _) -> bool;
   bif_return_type(is_list, [_], _) -> bool;
   bif_return_type(is_map, [_], _) -> bool;
  
positive.code: bif_return_type(is_tuple, [_], _) -> bool;
  %% Misc.
  bif_return_type(tuple_size, [_], _) -> {integer,[]};
  bif_return_type(node, [], _) -> {atom,[]};
  bif_return_type(node, [_], _) -> {atom,[]};
  bif_return_type(hd, [_], _) -> term;
  
negative.code: bif_arg_types('bit_size', [_]) -> [binary];
  %% Numerical
  bif_arg_types('-', [_]) -> [number];
  bif_arg_types('-', [_,_]) -> [number,number];
  bif_arg_types('+', [_]) -> [number];
  bif_arg_types('+', [_,_]) -> [number,number];
  bif_arg_types('*', [_,_]) -> [number, number];
  bif_arg_types('/', [_,_]) -> [number, number];
  bif_arg_types(abs, [_]) -> [number];
  bif_arg_types(ceil, [_]) -> [number];
  bif_arg_types(float, [_]) -> [number];
  bif_arg_types(floor, [_]) -> [number];
  bif_arg_types(trunc, [_]) -> [number];
  bif_arg_types(round, [_]) -> [number];
  