code: def get(self, tag, nth=1):
          
  
          tag = fix_tag(tag)
          nth = int(nth)
  
          for t, v in self.pairs:
              if t == tag:
                  nth -= 1
                  if nth == 0:
                      return v
  
          return None
docs: Return n-th value for tag.
  
          :param tag: FIX field tag number.
          :param nth: Index of tag if repeating, first is 1.
          :return: None if nothing found, otherwise value matching tag.
  
          Defaults to returning the first matching value of 'tag', but if
          the 'nth' parameter is overridden, can get repeated fields.