text: from hwt.synthesizer.unit import Unit
  from hwt.interfaces.std import Signal
  
  
  class CustomSignal(Signal):
      "Doc for a CustomSignal class itself"
  
  
  class ExampleCls0(Unit):
      """
      .. hwt-interfaces::
      """
  
      def _declr(self):
          self.din = CustomSignal()
          self.dout = CustomSignal()._m()
  
      def _impl(self):
          self.dout(self.din)
  