code: def _positions_to_examine(db_file):
      
      conn = sqlite3.connect(db_file)
      cursor = conn.cursor()
      cursor.execute("""SELECT MAX(position) FROM data""")
      position = cursor.fetchone()[0]
      if position is not None:
          position = int(position)
      cursor.close()
      split_at = 50
      if position is None:
          return []
      elif position < split_at:
          return [("<= %s" % position, "lt%s" % position)]
      else:
          return [("< %s" % split_at, "lt%s" % split_at),
                  (">= %s" % split_at, "gt%s" % split_at)]
docs: Determine how to sub-divide recalibration analysis based on read length.