// zero value of sparseHoles logically represents a normal file (i.e., there are
// no holes in it). On the other hand, the zero value of sparseDatas implies
// that the file has no data in it, which is rather odd.
//
// As an example, if the underlying raw file contains the 10-byte data:
//
//	var compactFile = "abcdefgh"
//
// And the sparse map has the following entries:
//
//	var spd sparseDatas = []sparseEntry{

		[]byte("\xc0a\xc0"),
		[]byte("\xc0a\xc0cd"),
		[]byte("ab\xc0a\xc0")},
	{not(isValidRune), "\xc0a\xc0",
		[]byte("a"),
		[]byte("a\xc0"),
		[]byte("\xc0a")},
	// The nils returned by TrimLeftFunc are odd behavior, but we need
	// to preserve backwards compatibility.
	{isSpace, "",
		nil,
		nil,
		[]byte("")},
	{isSpace, " ",
		nil,
		nil,
		[]byte("")},
}