text: import string
  
  from django.conf import settings
  from django.core.exceptions import ImproperlyConfigured
  from django.template import Origin, TemplateDoesNotExist
  from django.utils.html import conditional_escape
  
  from .base import BaseEngine
  from .utils import csrf_input_lazy, csrf_token_lazy
  
  
  class TemplateStrings(BaseEngine):
  
      app_dirname = 'template_strings'
  
      def __init__(self, params):
          params = params.copy()
          options = params.pop('OPTIONS').copy()
          if options:
              raise ImproperlyConfigured(
                  "Unknown options: {}".format(", ".join(options)))
          super(TemplateStrings, self).__init__(params)
  
      def from_string(self, template_code):
          return Template(template_code)
  
      def get_template(self, template_name):
          tried = []
          for template_file in self.iter_template_filenames(template_name):
              try:
                  with open(template_file, encoding=settings.FILE_CHARSET) as fp:
                      template_code = fp.read()
              except FileNotFoundError:
                  tried.append((
                      Origin(template_file, template_name, self),
                      'Source does not exist',
                  ))
                  continue
  
              return Template(template_code)
  
          else:
              raise TemplateDoesNotExist(template_name, tried=tried, backend=self)
  
  
  class Template(string.Template):
  
      def render(self, context=None, request=None):
          if context is None:
              context = {}
          else:
              context = {k: conditional_escape(v) for k, v in context.items()}
          if request is not None:
              context['csrf_input'] = csrf_input_lazy(request)
              context['csrf_token'] = csrf_token_lazy(request)
          return self.safe_substitute(context)
  