code: func (pk PrivKeyLedgerSecp256k1) ValidateKey() error {
  	// getPubKey will return an error if the ledger is not
  	pub, err := pk.getPubKey()
  	if err != nil {
  		return err
  	}
  	// verify this matches cached address
  	if !pub.Equals(pk.CachedPubKey) {
  		return fmt.Errorf("cached key does not match retrieved key")
  	}
  	return nil
  }
docs: // ValidateKey allows us to verify the sanity of a key
  // after loading it from disk