code: def find_free_prefix(self, args):
          
  
          try:
              return self.nip.find_free_prefix(args.get('auth'), args.get('vrf'), args.get('args'))
          except NipapError as exc:
              self.logger.debug(unicode(exc))
              raise Fault(exc.error_code, unicode(exc))
docs: Find a free prefix.
  
              Valid keys in the `args`-struct:
  
              * `auth` [struct]
                  Authentication options passed to the :class:`AuthFactory`.
              * `args` [struct]
                  Arguments for the find_free_prefix-function such as what prefix
                  or pool to allocate from.