code: def version(self, content_type="*/*"):
          
          v = ""
          accept_header = self.get_header('accept', "")
          if accept_header:
              a = AcceptHeader(accept_header)
              for mt in a.filter(content_type):
                  v = mt[2].get("version", "")
                  if v: break
  
          return v
docs: versioning is based off of this post 
          http://urthen.github.io/2013/05/09/ways-to-version-your-api/