docs: def start_transmit(self, blocking=False, start_packet_groups=True, *ports):
          """ Start transmit on ports.
  
          :param blocking: True - wait for traffic end, False - return after traffic start.
          :param start_packet_groups: True - clear time stamps and start collecting packet groups stats, False - don't.
          :param ports: list of ports to start traffic on, if empty start on all ports.
          """
  
          port_list = self.set_ports_list(*ports)
          if start_packet_groups:
              port_list_for_packet_groups = self.ports.values()
              port_list_for_packet_groups = self.set_ports_list(*port_list_for_packet_groups)
              self.api.call_rc('ixClearTimeStamp {}'.format(port_list_for_packet_groups))
              self.api.call_rc('ixStartPacketGroups {}'.format(port_list_for_packet_groups))
          self.api.call_rc('ixStartTransmit {}'.format(port_list))
          time.sleep(0.2)
  
          if blocking:
              self.wait_transmit(*ports)