Generally we put comments on the line above the one they comment, indented to the same level that of the line that they are commenting.  Also, PEP8 says to put one space between the `#` and the text.  So this would look like:

```python
    # americium 242 - ZZZAAA : 095 242 - Excited state dropped..
    assert_equal(nucname.zzzaaa("AM242M"), 95242)
```