build/operation.go
func (m SourceAccount) MutateOperation(o *xdr.Operation) error {
	o.SourceAccount = &xdr.AccountId{}
	return setAccountId(m.AddressOrSeed, o.SourceAccount)
}
func (m SourceAccount) MutateOperation(o *xdr.Operation) error {
	o.SourceAccount = &xdr.AccountId{}
	return setAccountId(m.AddressOrSeed, o.SourceAccount)
}
// MutateOperation for SourceAccount sets the operation's SourceAccount
// to the pubilic key for the address provided