Has anyone here implemented an indicator that returns weights for assets in a portfolio? Here is the Strategy version:

```
class WeighInverseVol(bt.Strategy):
def __init__(self):
rs = [bt.ind.PctChange(d.close, period=1) for d in self.datas]
vs = [bt.ind.StdDev(ret, period=30) for ret in rs]
inv = [bt.DivByZero(bt.LineNum(1), v) for v in vs]
invsum = bt.LineNum(0)
for inv_ in inv:
invsum += inv_
# self.weights is an array of asset allocation weights
# one weight per asset in self.datas
self.weights = [inv_ / invsum for inv_ in inv]
```

I'd like `WeighInverseVol`

to be an Indicator so I can use it within other strategies but I don't know how to return a dynamic number of lines within an indicator. Any advice?

Thanks!