code: def _do_nofx(transactions, arguments):
      
      try:
          num, family = arguments.split(',')
          limit = int(num.strip())
      except ValueError:
          LOGGER.warning("Ignore, NofX requires arguments in the format "
                         "int,family not %s", arguments)
          return True
      count = 0
      family = family.strip()
      for txn in transactions:
          header = TransactionHeader()
          header.ParseFromString(txn.header)
          if header.family_name == family:
              count += 1
  
          if count > limit:
              LOGGER.debug("Too many transactions of type %s", family)
              return False
  
      return True
docs: Only N of transaction type X may be included in a block. The first
      argument must be interpretable as an integer. The second argument is
      interpreted as the name of a transaction family. For example, the
      string "NofX:2,intkey" means only allow 2 intkey transactions per
      block.