Is it possible to easily remove NaN values for a Python Set object? Given that NaN values do not equal anything (and `float('nan') is float('nan')` is also `False`), you can end up with many NaN values in a Set.

```
>>> a = set( (float('nan'), float('nan'), 'a') )
>>> a
{nan, nan, 'a'}

```

The best I can come up with it to define a function like math.isnan, but that is tolerant of non-float types like:

```
def my_isnan(x):
    try:
        return math.isnan(x)
    except TypeError:
        return False

```

Then you can use a set comprehension like this:

```
>>> {x for x in a if not my_isnan(x)}
{'a'}

```