text: import rospy
  from geometry_msgs.msg import Twist
  
  pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
  
  from ipywidgets import Button, HBox, VBox
  from IPython.display import display
  
  def on_button_clicked(b):
      v = Twist()
      if b.description=='forward':
          v.linear.x = 2.0
      elif b.description=='backward':
          v.linear.x = -2.0
      elif b.description=='left':
          v.angular.z = 2.0
      elif b.description=='right':
          v.angular.z = -2.0
      pub.publish(v)
  
  words = ['forward', 'backward', 'left', 'right']
  items = [Button(description=w) for w in words]
  for button in items:
      button.on_click(on_button_clicked)
  
  left_box = VBox([items[0], items[1]])
  right_box = VBox([items[2], items[3]])
  display(HBox([left_box, right_box]))