code: def filter_for_ringspan(clearnacs, spanlimit):
      "filter for covered ringspan, giver in km."
      delta = clearnacs.MAXIMUM_RING_RADIUS - clearnacs.MINIMUM_RING_RADIUS
      f = delta < spanlimit
      ringspan = clearnacs[f].copy()
      return ringspaf filter_for_ringspan(clearnacs, spanlimit):
      "filter for covered ringspan, giver in km."
      delta = clearnacs.MAXIMUM_RING_RADIUS - clearnacs.MINIMUM_RING_RADIUS
      f = delta < spanlimit
      ringspan = clearnacs[f].copy()
      return ringspan
docs: filter for covered ringspan, giver in km.