如何检查一个类是否为它定义了operator <<？

Question

如何检查std::cout << myClass;是否有效？我想做类似的事情：

class Logger {
 public:
  // Some kind of enable_if(operator<< doesn't exist)
  void printMyClass(MyClass& my_class) {
    std::cout << "Got a myclass" << std::endl;
  }   

  // Some kind of enable_if(operator<< exists)
  void printMyClass(MyClass& my_class) {
    std::cout << "Got a myclass: " << my_class << std::endl;
  }   

};