svoid forwardSwappableFunctionToObject(O o, S methodName, O target) {
  forwardSwappableFunctionToObject(o, methodName, target, methodName);
}

svoid forwardSwappableFunctionToObject(O o, S methodName, O target, S methodNameOnTarget) {
  if (o == null || target == null) ret;
  Class type = fieldType(o, field);
  if (type == null) ret; // field doesn't exist
  S proxyMethodName = type == Runnable ? "run" : "get";
  set(o, field, singleObjectMethodProxy2(type, target, proxyMethodName, methodName));
}