type io.ReaderAt

4 uses

	io (current package)
		io.go#L225: type ReaderAt interface {
		io.go#L480: func NewSectionReader(r ReaderAt, off int64, n int64) *SectionReader {
		io.go#L487: 	r     ReaderAt

	mime/multipart
		formdata.go#L169: 	io.ReaderAt