func (meta *Meta) Next(n uint64) (pos uint64, err error) {
	meta.Lock()
	defer meta.Unlock()

	pos = meta.data.End
	meta.data.End += n
	err = meta.save()
	return
}
// Next pointer in file for writing [n] number of bytes.
Next pointer in file for writing [n] number of bytes.
// Next pointer in file for writing [ n ] number of bytes .
func (meta *Meta) Next(n uint64) (pos uint64, err error) {
	meta.Lock()
	defer meta.Unlock()
	pos = meta.data.End
	meta.data.End += n
	err = meta.save()
	return
}
func ( meta * Meta ) Next ( n uint64 ) ( pos uint64 , err error ) { meta . Lock ( ) defer meta . Unlock ( ) pos = meta . data . End meta . data . End += n err = meta . save ( ) return }
Next pointer in file for writing [n] number of bytes.
Next pointer in file for writing [ n ] number of bytes .