append_va (GString *string,
           va_list va)
{
  const gchar *name;
  const gchar *value;
  guint seen = 0;

  for (;;)
    {
      name = va_arg (va, const gchar *);
      if (!name)
        break;
      value = va_arg (va, const gchar *);
      seen |= append_header (string, name, value);
    }

  return seen;
}
append_va (GString *string,
           va_list va)
{
  const gchar *name;
  const gchar *value;
  guint seen = 0;

  for (;;)
    {
      name = va_arg (va, const gchar *);
      if (!name)
        break;
      value = va_arg (va, const gchar *);
      seen |= append_header (string, name, value);
    }

  return seen;
}