code: def find_minmax(lims, olims):
      
      try:
          limzip = zip(list(lims), list(olims), [np.nanmin, np.nanmax])
          limits = tuple([float(fn([l, ol])) for l, ol, fn in limzip])
      except:
          limits = (np.NaN, np.NaN)
      return limits
docs: Takes (a1, a2) and (b1, b2) as input and returns
      (np.nanmin(a1, b1), np.nanmax(a2, b2)). Used to calculate
      min and max values of a number of items.