docs: def postcode(self):
          """
          Replaces all question mark ('?') occurrences with a random letter
          from postal_code_formats then passes result to
          numerify to insert numbers
          """
          temp = re.sub(r'\?',
                        lambda x: self.postal_code_letter(),
                        self.random_element(self.postal_code_formats))
          return self.numerify(temp)