func (file *GridFile) Abort() {
	if file.mode != gfsWriting {
		panic("file.Abort must be called on file opened for writing")
	}
	file.err = errors.New("write aborted")
}
func (file *GridFile) Abort() {
	if file.mode != gfsWriting {
		panic("file.Abort must be called on file opened for writing")
	}
	file.err = errors.New("write aborted")
}
// Abort cancels an in-progress write, preventing the file from being
// automically created and ensuring previously written chunks are
// removed when the file is closed.
//
// It is a runtime error to call Abort when the file was not opened
// for writing.