docs: def read_template_source(filename):
      """Read the source of a Django template, returning the Unicode text."""
      # Import this late to be sure we don't trigger settings machinery too
      # early.
      from django.conf import settings
  
      if not settings.configured:
          settings.configure()
  
      with open(filename, "rb") as f:
          text = f.read().decode(settings.FILE_CHARSET)
  
      return text