Question/Suggestion : Window or Rolling does not have a `get_window` public method 
#### Code Sample, a copy-pastable example if possible

```python
# somewhere
rolling = df.rolling(7, win_type="bartlett")

#somewhere else 
plot( rolling._get_window( win_type=rolling.win_type) ) 
```
#### Problem description

Sometime you receive a Rolling or Window from somewhere and want, e.g. plot its shape. 
Would be convenient to have a public method or property to get the array window weight instead of  private `._get_window` method. 
could not found one. 