code: def set_code(self, idx):
          
  
          code = self.format[idx:idx + 3]
  
          if len(code) < 3 or not code.isdigit():
              return False
  
          self.codes.append(int(code))
          self.ignore = 2
          self.code_last = True
          return True
docs: Sets a code to be filtered on for the conversion.  Note that
          this also sets the 'code_last' attribute and configures to
          ignore the remaining characters of the code.
  
          :param idx: The index at which the code _begins_.
  
          :returns: True if the code is valid, False otherwise.