NewCleanupReadCloser creates an io.ReadCloser that calls the cleanup function after closing the original closer.

WriterToReader transforms an io.Writer that is provided by the given function into an io.Reader.

CleanupReadCloser wraps an io.ReadCloser and a function to be called on Close.

LatencyReader wraps an io.Reader and introduces a delay before each read.

CloserFunc is the basic Close method defined in io.Closer.