horizon/main.go
func (c *Client) SequenceForAccount(
	accountID string,
) (xdr.SequenceNumber, error) {

	a, err := c.LoadAccount(accountID)
	if err != nil {
		return 0, err
	}

	seq, err := strconv.ParseUint(a.Sequence, 10, 64)
	if err != nil {
		return 0, err
	}

	return xdr.SequenceNumber(seq), nil
}
func (c *Client) SequenceForAccount(
	accountID string,
) (xdr.SequenceNumber, error) {

	a, err := c.LoadAccount(accountID)
	if err != nil {
		return 0, err
	}

	seq, err := strconv.ParseUint(a.Sequence, 10, 64)
	if err != nil {
		return 0, err
	}

	return xdr.SequenceNumber(seq), nil
}
// SequenceForAccount implements build.SequenceProvider