IntervalVector pretty-printting bug with Python

Trying to pretty-print the following interval vector with `icecream` raises a `TypeError`
```
from codac import *
from icecream import ic
b2_iv = IntervalVector([[-0.5418019655155, -0.4680189629224],[-0.4088904965983, -0.3177809931966]])
ic(b2_iv)
```