title: Which namespace does operator<< (stream) go to?
body: <p>If I have have some overloaded ostream operators, defined for library local objects, is its okay for them to go to std namespace? If I do not declare them in std namespace, then I must use <code>using ns:: operator &lt;&lt;</code>.</p>
  
  <p>As a possible follow-up question, are there any operators which should go to standard or global namespace?</p>