static S evalJava_prep(S code) {
  ret evalJava_prep(code, "calc");
}

static S evalJava_prep(S code, S mainName) {
  ret evalJava_prep(code, mainName, "");
}

static S evalJava_prep(S code, S mainName, S preCode) {
  L<S> tok = javaTok(trim(code));
  
  if (tok_shouldAddReturn(tok) && eqGet(tok, 3, "(") && isIdentifier(get(tok, 1)) && isKnownVoidFunction(get(tok, 1))))
    tokAppend_reTok(tok, l(tok)-2, ";");
    
  code = tok_addReturn(tok);
  S returnType = containsReturnWithArgument(code) ? "O" : "void";
  S main = // "!include #1003911\n" + // functions for quick eval
    "static " + returnType + " " + mainName + "() throws Exception { " 
      + preCode + code + "\n" + "}";
  ret main;
}