sS tb_mainServer_default = "http://tinybrain.de:8080";
static O tb_mainServer_override; // func -> S

static S tb_mainServer() {
  if (tb_mainServer_override != null) ret (S) callF(tb_mainServer_override);
  ret trim(loadTextFile(getProgramFile(#1001638, "mainserver.txt"),
    tb_mainServer_default));
}