FOR loops - lists of invoices

The Send multiple invoices email template includes a list of invoices.

{% set sum_of_invoice_balances = 0 %}

{% for invoice in invoices %}
   * Invoice {{ invoice.refnumber }} - balance: {{ invoice.balance|number_format(2) }}
   {% set sum_of_invoice_balances = sum_of_invoice_balances + invoice.balance %}
{% endfor %}

Total balance due: {{ sum_of_invoice_balances|number_format(2) }}