code: def variables(self):
          
          string = str(self)
          constants = [match[1:-1] for match in re.findall('{{[A-z0-9]}}', string)]
          variables = re.findall('{[A-z0-9]*}', string)
          return sorted(set(variables).difference(constants))
docs: Display a list of templatable variables present in the file.
  
          Templating is accomplished by creating a bracketed object in the same
          way that Python performs `string formatting`_. The editor is able to
          replace the placeholder value of the template. Integer templates are
          positional arguments.
  
          .. _string formatting: https://docs.python.org/3.6/library/string.html