code: def cmd_do_change_speed(self, args):
          '''speed value'''
          if ( len(args) != 1):
              print("Usage: setspeed SPEED_VALUE")
              return
  
          if (len(args) == 1):
              speed = float(args[0])
              print("SPEED %s" % (str(speed)))
              self.master.mav.command_long_send(
                  self.settings.target_system,  # target_system
                  mavutil.mavlink.MAV_COMP_ID_SYSTEM_CONTROL, # target_component
                  mavutil.mavlink.MAV_CMD_DO_CHANGE_SPEED, # command
                  0, # confirmation
                  0, # param1
                  speed, # param2 (Speed value)
                  0, # param3
                  0, # param4
                  0, # param5
                  0, # param6
                  0f cmd_do_change_speed(self, args):
          '''speed value'''
          if ( len(args) != 1):
              print("Usage: setspeed SPEED_VALUE")
              return
  
          if (len(args) == 1):
              speed = float(args[0])
              print("SPEED %s" % (str(speed)))
              self.master.mav.command_long_send(
                  self.settings.target_system,  # target_system
                  mavutil.mavlink.MAV_COMP_ID_SYSTEM_CONTROL, # target_component
                  mavutil.mavlink.MAV_CMD_DO_CHANGE_SPEED, # command
                  0, # confirmation
                  0, # param1
                  speed, # param2 (Speed value)
                  0, # param3
                  0, # param4
                  0, # param5
                  0, # param6
                  0)
docs: speed value