docs: def get_pos(self, sector):
          """Get index (into the raw data of the disk image) of start of sector
  
          This base class method assumes the sectors are one after another, in
          order starting from the beginning of the raw data.
          """
          if not self.sector_is_valid(sector):
              raise ByteNotInFile166("Sector %d out of range" % sector)
          pos = sector * self.sector_size + self.header_offset
          size = self.sector_size
          return pos, size