>>> size = 9
>>> x = [(" "*(int(size/2)-i) + "*" + (" "*((i*2)+1)) + "*") for i in range(int(size/2))[::-1]]
>>> x.extend(["*".center(size+2)] + x[::-1])
>>> print('\n'.join(x))
 *       *
  *     *
   *   *
    * *
     *
    * *
   *   *
  *     *
 *       *
>>>