text: import os
  from django.template.loader import get_template, TemplateDoesNotExist
  from cmsplugin_cascade import app_settings
  from cmsplugin_cascade.plugin_base import CascadePluginBase
  
  
  class BootstrapPluginBase(CascadePluginBase):
      module = 'Bootstrap'
      require_parent = True
      allow_children = True
      render_template = 'cascade/generic/wrapper.html'
  
      def get_render_template(self, context, instance, placeholder):
          render_template = getattr(self, 'render_template', None)
          if render_template and '{}' in render_template:
              try:
                  # check if overridden template exists
                  template = render_template.format(app_settings.CMSPLUGIN_CASCADE['bootstrap4']['template_basedir'])
                  template = os.path.normpath(template)
                  get_template(template)
                  return template
              except (KeyError, TemplateDoesNotExist):
                  template = render_template.format('')
                  return os.path.normpath(template)
          return render_template
  