code: def find_free(cls, vrf, args):
          
  
          xmlrpc = XMLRPCConnection()
          q = {
              'args': args,
              'auth': AuthOptions().options
          }
  
          # sanity checks
          if isinstance(vrf, VRF):
              q['vrf'] = { 'id': vrf.id }
          elif vrf is None:
              q['vrf'] = None
          else:
              raise NipapValueError('vrf parameter must be instance of VRF class')
  
          # run XML-RPC query
          try:
              find_res = xmlrpc.connection.find_free_prefix(q)
          except xmlrpclib.Fault as xml_fault:
              raise _fault_to_exception(xml_fault)
          pass
  
          return find_res
docs: Finds a free prefix.
  
              Maps to the function
              :py:func:`nipap.backend.Nipap.find_free_prefix` in the backend.
              Please see the documentation for the backend function for
              information regarding input arguments and return values.