title: Median of a list with NaN values removed, in python
body: <p>Is it possible to calculate the median of a list without explicitly removing the NaN's, but rather, ignoring them?</p>
  
  <p>I want <code>median([1,2,3,NaN,NaN,NaN,NaN,NaN,NaN])</code> to be 2, not NaN. </p>