func (sa *SectorAllocator) Allocated() uint32 {
	return uint32(sa.next)
}
Returns the total number of sectors allocated
package iso9660
const (
	LogicalBlockSize = 2048
)
type LogicalBlockAddress uint32
type SectorAllocator struct {
	next LogicalBlockAddress
}
func NewSectorAllocator() *SectorAllocator {
	return &SectorAllocator{0}
}
func (sa *SectorAllocator) Alloc(numBytes uint32) LogicalBlockAddress {
	result := sa.next
	sa.next += LogicalBlockAddress(bytesToSectors(numBytes))
	return result
}