text: 
  #############################################################################
  ##
  ## Copyright (C) 2010 velociraptor Genjix <aphidia@hotmail.com>
  ## Copyright (C) 2016 The Qt Company Ltd.
  ## Contact: http://www.qt.io/licensing/
  ##
  ## This file is part of the Qt for Python examples of the Qt Toolkit.
  ##
  ## $QT_BEGIN_LICENSE:BSD$
  ## You may use this file under the terms of the BSD license as follows:
  ##
  ## "Redistribution and use in source and binary forms, with or without
  ## modification, are permitted provided that the following conditions are
  ## met:
  ##   * Redistributions of source code must retain the above copyright
  ##     notice, this list of conditions and the following disclaimer.
  ##   * Redistributions in binary form must reproduce the above copyright
  ##     notice, this list of conditions and the following disclaimer in
  ##     the documentation and/or other materials provided with the
  ##     distribution.
  ##   * Neither the name of The Qt Company Ltd nor the names of its
  ##     contributors may be used to endorse or promote products derived
  ##     from this software without specific prior written permission.
  ##
  ##
  ## THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ## "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ## LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ## A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  ## OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  ## SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  ## LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  ## DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  ## THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  ## (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  ## OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
  ##
  ## $QT_END_LICENSE$
  ##
  #############################################################################
  
  from PySide2.QtWidgets import *
  from PySide2.QtGui import *
  from PySide2.QtCore import *
  
  class LightWidget(QWidget):
      def __init__(self, color):
          super(LightWidget, self).__init__()
          self.color = color
          self.onVal = False
      def isOn(self):
          return self.onVal
      def setOn(self, on):
          if self.onVal == on:
              return
          self.onVal = on
          self.update()
      @Slot()
      def turnOff(self):
          self.setOn(False)
      @Slot()
      def turnOn(self):
          self.setOn(True)
      def paintEvent(self, e):
          if not self.onVal:
              return
          painter = QPainter(self)
          painter.setRenderHint(QPainter.Antialiasing)
          painter.setBrush(self.color)
          painter.drawEllipse(0, 0, self.width(), self.height())
  
      on = Property(bool, isOn, setOn)
  
  class TrafficLightWidget(QWidget):
      def __init__(self):
          super(TrafficLightWidget, self).__init__()
          vbox = QVBoxLayout(self)
          self.redLight = LightWidget(Qt.red)
          vbox.addWidget(self.redLight)
          self.yellowLight = LightWidget(Qt.yellow)
          vbox.addWidget(self.yellowLight)
          self.greenLight = LightWidget(Qt.green)
          vbox.addWidget(self.greenLight)
          pal = QPalette()
          pal.setColor(QPalette.Background, Qt.black)
          self.setPalette(pal)
          self.setAutoFillBackground(True)
  
  def createLightState(light, duration, parent=None):
      lightState = QState(parent)
      timer = QTimer(lightState)
      timer.setInterval(duration)
      timer.setSingleShot(True)
      timing = QState(lightState)
      timing.entered.connect(light.turnOn)
      timing.entered.connect(timer.start)
      timing.exited.connect(light.turnOff)
      done = QFinalState(lightState)
      timing.addTransition(timer, SIGNAL('timeout()'), done)
      lightState.setInitialState(timing)
      return lightState
  
  class TrafficLight(QWidget):
      def __init__(self):
          super(TrafficLight, self).__init__()
          vbox = QVBoxLayout(self)
          widget = TrafficLightWidget()
          vbox.addWidget(widget)
          vbox.setContentsMargins(0, 0, 0, 0)
  
          machine = QStateMachine(self)
          redGoingYellow = createLightState(widget.redLight, 1000)
          redGoingYellow.setObjectName('redGoingYellow')
          yellowGoingGreen = createLightState(widget.redLight, 1000)
          yellowGoingGreen.setObjectName('redGoingYellow')
          redGoingYellow.addTransition(redGoingYellow, SIGNAL('finished()'), yellowGoingGreen)
          greenGoingYellow = createLightState(widget.yellowLight, 3000)
          greenGoingYellow.setObjectName('redGoingYellow')
          yellowGoingGreen.addTransition(yellowGoingGreen, SIGNAL('finished()'), greenGoingYellow)
          yellowGoingRed = createLightState(widget.greenLight, 1000)
          yellowGoingRed.setObjectName('redGoingYellow')
          greenGoingYellow.addTransition(greenGoingYellow, SIGNAL('finished()'), yellowGoingRed)
          yellowGoingRed.addTransition(yellowGoingRed, SIGNAL('finished()'), redGoingYellow)
  
          machine.addState(redGoingYellow)
          machine.addState(yellowGoingGreen)
          machine.addState(greenGoingYellow)
          machine.addState(yellowGoingRed)
          machine.setInitialState(redGoingYellow)
          machine.start()
  
  if __name__ == '__main__':
      import sys
      app = QApplication(sys.argv)
      widget = TrafficLight()
      widget.resize(110, 300)
      widget.show()
      sys.exit(app.exec_())
  