code: func parsePubkey(in string) (*ecdsa.PublicKey, error) {
  	b, err := hex.DecodeString(in)
  	if err != nil {
  		return nil, err
  	} else if len(b) != 64 {
  		return nil, fmt.Errorf("wrong length, want %d hex chars", 128)
  	}
  	b = append([]byte{0x4}, b...)
  	return crypto.UnmarshalPubkey(b)
  }
docs: // parsePubkey parses a hex-encoded secp256k1 public key.