anchor.diff:  %% maps module
   expr_fun({Op, A}) when Op=='map_size' ->
       module_fun('maps', {size, A});
  +expr_fun({Op, A, B}) when Op=='map_get';Op=='map_merge';Op=='map_remove';Op=='map_with';Op=='map_without'->
  +    module_fun('maps', {Op, A, B});
   %% Logical expressions
   expr_fun({'not', A}) ->
       case expr_fun(A) of
  
positive.code:             , to_tuple, to_list, to_map, to_term, to_binterm, to_pid, from_binterm
              , to_decimal, from_decimal, to_timestamp, to_datetime, to_ipaddr
              , to_json, json_to_list, json_arr_proj, json_obj_proj, json_value, json_diff, md5
              , byte_size, bit_size, map_size, nth, sort, usort, reverse, last, remap, phash2
              , '[]', '{}', ':', '#keys', '#key','#values','#value', '::'
              , mfa
              ]).
  
negative.code:         JO when is_binary(JO) -> JO;
          _ ->    B
      end;
  to_json(L) when is_list(L) ->
      case catch imem_json:encode(L) of 
          JO when is_binary(JO) -> JO;
          _ ->    ?nav
      end;
  to_json(M) when is_map(M) ->  imem_json:encode(M);
  to_json(_) -> ?nav.
  
  to_pid(T) when is_pid(T) -> T;
  to_pid(B) -> imem_datatype:io_to_pid(B).
  