code: def change_speed(body, speed=1):
      
      if speed == 1:
          return body
  
      length = int(len(body) * speed)
      rv = bytearray(length)
  
      step = 0
      for v in body:
          i = int(step)
          while i < int(step + speed) and i < length:
              rv[i] = v
              i += 1
          step += speed
      return rv
docs: Change the voice speed of the wave body.