code: def count_braces(self):
      
      n_left = len(re.findall("{{", self.template))
      n_right = len(re.findall("}}", self.template))
      return n_left, n_right
docs: returns a count of "{{" and "}}" in the template, as (N_left_braces, N_right_braces)
      Useful to check after resolve() has run, to infer that template has an error since no {{ or }}
      should be present in the template after resolve()