title: what does this declaration mean? exception() throw()
body: <p>std::exception class is defined as follows</p>
  
  <pre><code>exception() throw() { }
  virtual ~exception() throw();
  virtual const char* what() const throw();
  </code></pre>
  
  <p>what does the throw() syntax mean in a declaration?
  Can throw() take parameters? What does no parameters mean?</p>