code: func ToReadCloser(r io.Reader) io.ReadCloser {
  	if rc, ok := r.(io.ReadCloser); ok {
  		return rc
  	}
  
  	return struct {
  		io.Reader
  		io.Closer
  	}{
  		r,
  		ioutil.NopCloser(nil),
  	}
  }
docs: // ToReadCloser creates an io.ReadCloser from the given io.Reader.
  // If it's not already, one will be created with a Close method that does nothing.