# can sage identify poles in or out the unit disk

i want to calculate residues on the unit disk, but in the factorization of the functions i work with i have roots or poles in and out the unit disk but i'm interested only in the ones inside the unit disk.

```
f(t)=\frac{1}{t^{-1}(t-z_1)(t-z_2)}, |z_1|<1<|z_2|,
```

There is a way that sage identify the poles i want and work with those?

Your question is very vague. What is your function? Why do you want to do with its poles?