code: def get_speed_steering(self, steering, speed):
          
  
          assert steering >= -100 and steering <= 100,\
              "{} is an invalid steering, must be between -100 and 100 (inclusive)".format(steering)
  
          # We don't have a good way to make this generic for the pair... so we
          # assume that the left motor's speed stats are the same as the right
          # motor's.
          speed = self.left_motor._speed_native_units(speed)
          left_speed = speed
          right_speed = speed
          speed_factor = (50 - abs(float(steering))) / 50
  
          if steering >= 0:
              right_speed *= speed_factor
          else:
              left_speed *= speed_factor
  
          return (left_speed, right_speed)
docs: Calculate the speed_sp for each motor in a pair to achieve the specified
          steering. Note that calling this function alone will not make the
          motors move, it only calculates the speed. A run_* function must be called
          afterwards to make the motors move.
  
          steering [-100, 100]:
              * -100 means turn left on the spot (right motor at 100% forward, left motor at 100% backward),
              *  0   means drive in a straight line, and
              *  100 means turn right on the spot (left motor at 100% forward, right motor at 100% backward).
  
          speed:
              The speed that should be applied to the outmost motor (the one
              rotating faster). The speed of the other motor will be computed
              automatically.