I have this DataFrame

```
df = pd.DataFrame({'A': [100, 100, 300, 200, 200, 200], 'B': [60, 55, 12, 32, 15, 44], 'C': ['x', 'x', 'y', 'y', 'y', 'y']})

```

and I want to sort it by columns "A" and "B". "A" is always ascending. I also want ascending for "B" if "C == x", else descending for "B" if "C == y". So it would end up like this

```
df_sorted = pd.DataFrame({'A': [100, 100, 200, 200, 200, 300], 'B': [55, 60, 44, 32, 15, 12], 'C': ['x', 'x', 'y', 'y', 'y', 'y']})

```