FYI, the type doesn't need a separate definition but can be an anonymous inline type too this:
```go
	tests := []struct {
		text   string
		sel    []Region
		expect string
	}{
		{
			"a\n\t  bc",
			[]Region{{1, 1}},
			"a bc",
		},
		{
			"abc\r\n\tde",
			[]Region{{0, 0}},
			"abc de",
		},
		{
			"testing \t\t\n join",
			[]Region{{9, 8}},
			"testing join",
		},
		{
			"test\n join\n command\n whith\n multiple\n regions",
			[]Region{{2, 17}, {34, 40}},
			"test join command whith\n multiple regions",
		},
	}
```

Not something that needs changing, just figured I'd comment on this