code: def get_template_from_request(request, page=None):
      
      page_templates = settings.get_page_templates()
      if len(page_templates) == 0:
          return settings.PAGE_DEFAULT_TEMPLATE
      template = request.REQUEST.get('template', None)
      if template is not None and \
              (template in dict(page_templates).keys() or
              template == settings.PAGE_DEFAULT_TEMPLATE):
          return template
      if page is not None:
          return page.get_template()
      return settings.PAGE_DEFAULT_TEMPLATE
docs: Gets a valid template from different sources or falls back to the
      default template.