code: def is_valid_sample(sent):
      tokens = sent.split(" ")
      return len(tokens) >= 1 and len(tokens) < 50
  
file_path: texar/examples/seq2seq_exposure_bias/utils/raml_samples_generation/process_samples.py
imports: from nltk.translate.bleu_score import sentence_bleu
  from nltk.translate.bleu_score import SmoothingFunction
  import sys
  import re
  import argparse
  import torch
  from util import read_corpus
  import numpy
  from scipy.misc import comb
  from vocab import Vocab, VocabEntry
  import math
  from rouge import Rouge
label_desc: Use image node_id 1 for calling a global function with example usage: is_valid_sample(sent) and returns: unknown