title: Boost::Bimap equivalent of bidirectional multimap
body: <p>First part of the question is that I am trying to use boost::bimap, but from the documentation it is unclear to me how to define a bidirectional multimap.</p>
  
  <p>The second part of the question is that I need it to be a map in one direction and a multimap in the other direction, can this be done using boost::bimap ?</p>
  
  <p>Has anyone experience of this or can point me to the correct page ?</p>