func (file *GridFile) Size() (bytes int64) {
	file.m.Lock()
	bytes = file.doc.Length
	file.m.Unlock()
	return
}
func (file *GridFile) Size() (bytes int64) {
	file.m.Lock()
	bytes = file.doc.Length
	file.m.Unlock()
	return
}
// Size returns the file size in bytes.