code: def find_nearest_locus(start, end, loci):
      
      best_distance = float("inf")
      best_locus = None
      for locus in loci:
          distance = locus.distance_to_interval(start, end)
          if best_distance > distance:
              best_distance = distance
              best_locus = locus
      return best_distance, best_locus
docs: Finds nearest locus (object with method `distance_to_interval`) to the
      interval defined by the given `start` and `end` positions.
      Returns the distance to that locus, along with the locus object itself.