I am to write a recursive function **printPattern()** that will output a pattern in stars. the first argument is always a power of 2 and is the max number of stars appearing in the middle row. The second argument (which defaults to 0) is the number of spaces to put before each patterns rows of stars.

an example of the output is:

```
>>> printPattern(8,0)
*
**
 *
****
  *
  **
   *
********
    *
    **
     *
    ****
      *
      **
       *

```

i have this code from a previous problem that is similar to what this is asking.

```
def patt(n,s=0):
    if n==1:
        print('*')
    else:
        patt(n-1)
        print('*'*n)
        patt(n-1)

```

im not really sure how to change it so that it only prints out powers of 2.