lint: fix issues in examples (#49)

examples/sha1/sha1.go

@@ -4,11 +4,13 @@ import (
 	"encoding/binary"
 )
 
-const (
-	Size      = 20
-	BlockSize = 64
-)
+// Size of a SHA-1 checksum in bytes.
+const Size = 20
 
+// BlockSize is the block size of SHA-1 in bytes.
+const BlockSize = 64
+
+// Sum returns the SHA-1 checksum of data.
 func Sum(data []byte) [Size]byte {
 	n := len(data)
 	h := [5]uint32{0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476, 0xc3d2e1f0}
@@ -21,7 +23,7 @@ func Sum(data []byte) [Size]byte {
 
 	// Final block.
 	tmp := make([]byte, BlockSize)
-	copy(tmp[:], data)
+	copy(tmp, data)
 	tmp[len(data)] = 0x80
 
 	if len(data) >= 56 {