xdr/ledger_key.go
func (key *LedgerKey) SetTrustline(account AccountId, line Asset) error {
	data := LedgerKeyTrustLine{account, line}
	nkey, err := NewLedgerKey(LedgerEntryTypeTrustline, data)
	if err != nil {
		return err
	}

	*key = nkey
	return nil
}
func (key *LedgerKey) SetTrustline(account AccountId, line Asset) error {
	data := LedgerKeyTrustLine{account, line}
	nkey, err := NewLedgerKey(LedgerEntryTypeTrustline, data)
	if err != nil {
		return err
	}

	*key = nkey
	return nil
}
// SetTrustline mutates `key` such that it represents the identity of the
// trustline owned by `account` and for `asset`.