code: def FindNext(params, ctxt, scope, stream, coord):
      
      if FIND_MATCHES_ITER is None:
          raise errors.InvalidState()
      
      direction = 1
      if len(params) > 0:
          direction = PYVAL(params[0])
      
      if direction != 1:
          # TODO maybe instead of storing the iterator in FIND_MATCHES_ITER,
          # we should go ahead and find _all the matches in the file and store them
          # in a list, keeping track of the idx of the current match.
          #
          # This would be highly inefficient on large files though.
          raise NotImplementedError("Reverse searching is not yet implemented")
      
      try:
          next_match = six.next(FIND_MATCHES_ITER)
          return next_match.start() + FIND_MATCHES_START_OFFSET
      except StopIteration as e:
          return -1
docs: This function returns the position of the next occurrence of the
      target value specified with the FindFirst function. If dir is 1, the
      find direction is down. If dir is 0, the find direction is up. The
      return value is the address of the found data, or -1 if the target
      is not found.