Clean-up and address PR comments

Author: nima

digest.go

@@ -83,7 +83,7 @@ func Parse(s string) (Digest, error) {
 	if err := d.Validate(); err != nil {
 		return "", err
 	}
-    return d, nil
+	return d, nil
 }
 
 // FromReader consumes the content of rd until io.EOF, returning canonical digest.

digestset/set.go

@@ -92,13 +92,14 @@ func (dst *Set) Lookup(d string) (digest.Digest, error) {
 		alg        digest.Algorithm
 		hex        string
 	)
-	dgst, err := digest.Parse(d)
+	_, err := digest.Parse(d)
 	if err == digest.ErrDigestInvalidFormat {
 		hex = d
 		searchFunc = func(i int) bool {
 			return dst.entries[i].val >= d
 		}
 	} else {
+		dgst := digest.Digest(d)
 		hex = dgst.Hex()
 		alg = dgst.Algorithm()
 		searchFunc = func(i int) bool {

verifiers.go

@@ -43,8 +43,10 @@ func (hv hashVerifier) Write(p []byte) (n int, err error) {
 
 func (hv hashVerifier) Verified() bool {
 	switch digest := NewDigest(hv.digest.Algorithm(), hv.hash); digest {
-	case hv.digest: return true
-	case FromString(""): return true
+	case hv.digest:
+		return true
+	case FromString(""):
+		return true
 	}
 
 	return false