code: func isGenerated(src []byte) bool {
  	sc := bufio.NewScanner(bytes.NewReader(src))
  	for sc.Scan() {
  		b := sc.Bytes()
  		if bytes.HasPrefix(b, genHdr) && bytes.HasSuffix(b, genFtr) && len(b) >= len(genHdr)+len(genFtr) {
  			return true
  		}
  	}
  	return false
  }
docs: // isGenerated reports whether the source file is generated code
  // according the rules from https://golang.org/s/generatedcode.