docs: def sorted_feed_cols(df):
      """
      takes a dataframe's columns that would be of the form:
      ['feed003', 'failsafe_feed999', 'override_feed000', 'feed001', 'feed002']
      and returns:
      ['override_feed000', 'feed001', 'feed002', 'feed003', 'failsafe_feed999']
      """
      cols = df.columns
      ind = [int(c.split("feed")[1]) for c in cols]
      cols = zip(ind,cols)
      cols.sort()
      cols = [c[1] for c in cols]
      return cols