anchor.diff:  unary_fun_result_type("to_atom") ->             #bind{type=atom,default=?nav};
   unary_fun_result_type("to_binary") ->           #bind{type=binary,default=?nav};
   unary_fun_result_type("to_binstr") ->           #bind{type=binstr,default=?nav};
  +unary_fun_result_type("list_to_binstr") ->      #bind{type=binstr,default=?nav};
   unary_fun_result_type("to_binterm") ->          #bind{type=binterm,default=?nav};
   unary_fun_result_type("to_boolean") ->          #bind{type=boolean,default=?nav};
   unary_fun_result_type("to_datetime") ->         #bind{type=datetime,default=?nav};
  
positive.code: %% Unary custom filters
  expr_fun({Op, A}) when Op==safe_atom;Op==safe_binary;Op==safe_binstr;Op==safe_binterm;Op==safe_boolean;Op==safe_datetime;Op==safe_decimal;Op==safe_integer;Op==safe_ipaddr;Op==safe_json;Op==safe_float;Op==safe_json;Op==safe_list;Op==safe_map;Op==safe_name;Op==safe_pid;Op==safe_string;Op==safe_term;Op==safe_text;Op==safe_timestamp;Op==safe_tuple ->
      safe_fun(A);
  expr_fun({Op, A}) when Op==to_atom;Op==to_binary;Op==to_binstr;Op==to_binterm;Op==to_boolean;Op==to_datetime;Op==to_decimal;Op==to_json;Op==to_float;Op==to_integer;Op==to_json;Op==to_list ->
      unary_fun({Op, A});
  expr_fun({Op, A}) when Op==to_map;Op==to_name;Op==to_number;Op==to_pid;Op==to_string;Op==to_term;Op==to_text;Op==to_timestamp;Op==to_time;Op==to_tuple ->
      unary_fun({Op, A});
  
negative.code: unary_fun_bind_type("map_size") ->              #bind{type=map,default= #{}};
  unary_fun_bind_type("from_binterm") ->          #bind{type=binterm,default= ?nav};
  unary_fun_bind_type("prefix_ul") ->             #bind{type=list,default= ?nav};
  unary_fun_bind_type("list_to_binstr") ->        #bind{type=list,default= ?nav};
  unary_fun_bind_type("json_to_list") ->          #bind{type=json,default= []};
  unary_fun_bind_type("phash2") ->                #bind{type=term,default= []};
  unary_fun_bind_type("md5") ->                   #bind{type=binstr,default= <<>>};
  