You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: dec_delta.go
    path of file: ./repos/scan4all/vendor/github.com/xi2/xz
    
    the code of the file until where you have to start completion: /*
 * Delta decoder
 *
 * Author: Lasse Collin <lasse.collin@tukaani.org>
 *
 * Translation to Go: Michael Cross <https://github.com/xi2>
 *
 * This file has been put into the public domain.
 * You can do whatever you want with this file
    
func xzDecDeltaRun(s *xzDecDelta, b *xzBuf, chain func(*xzBuf) xzRet) xzRet {
	outStart := b.outPos
	ret := chain(b)
	for i := outStart; i < b.outPos; i++ {
		tmp := b.out[i] + s.delta[byte(s.distance+int(s.pos))]
		s.delta[s.pos] = tmp
		b.out[i] = tmp
		s.pos--
	}
	return ret
}