assert g2p("dusta") == "ˈdʊsta"

hi,

is there any clue for this error ?

```
Traceback (most recent call last):
  File "/tb2/root/gitaudio/g2p-id/test_g2p.py", line 66, in <module>
    test_g2p_vocal()
  File "/tb2/root/gitaudio/g2p-id/test_g2p.py", line 61, in test_g2p_vocal
    assert g2p("dusta") == "ˈdʊsta"
AssertionError
```

