Comparing NaN to each other always results in False
I have a unittest set up that checks to make sure that a DataFrame has a NaN value in it, but am getting unexpected result. Here is code that shows the unexpected behavior:

from io import StringIO
def null():
    """ return a nan: is there a better way to do this? """
    return pd.read_csv(StringIO("NA\n"), header=None).loc[0][0]

null() == null()   # returns False

So how do I ensure that I am getting the expected "missing data" with this behavior?
