code: def download_and_process(
      file_url, mode, subreddit_names, st_time, output_dir
  ):
      # download and pre-process original posts
      reddit_tmp_dir = pjoin(output_dir, "reddit_tmp")
      f_name = pjoin(reddit_tmp_dir, file_url.split("/")[-1])
      tries_left = 4
      # open monthly dumps and download lines in posts
      while tries_left:
          try:
              print("downloading %s %2f" % (f_name, time() - st_time))
              subprocess.run(
                  ["wget", "-P", reddit_tmp_dir, file_url],
                  stdout=subprocess.PIPE,
              )
              print(
                  "decompressing and filtering %s %2f"
                  % (f_name, time() - st_time)
              )
              if f_name.split(".")[-1] == "xz":
                  f = lzma.open(f_name, "rt")
              elif f_name.split(".")[-1] == "bz2":
                  f = bz2.open(f_name, "rt")
              elif f_name.split(".")[-1] == "zst":
                  fh = open(f_name, "rb")
                  dctx = zstd.ZstdDecompressor()
                  stream_reader = dctx.stream_reader(fh)
                  f = io.TextIOWrapper(stream_reader, encoding="utf-8")
              lines = dict([(name, []) for name in subreddit_names])
              for i, l in enumerate(f):
                  if i % 1000000 == 0:
                      print(
                          "read %d lines, found %d"
                          % (
                              i,
                              sum([len(ls) for ls in lines.values()]),
                          ),
                          time() - st_time,
                      )
                  for name in subreddit_names:
                      subreddit_field = f'"subreddit":"{name}"'
                      if subreddit_field in l:
                          lines[name] += [l.strip()]
              if f_name.split(".")[-1] == "zst":
                  fh.close()
              else:
                  f.close()
              PathManager.rm(f_name)
              tries_left = 0
  
          except EOFError:
              sleep(10)
              print(
                  "failed reading file %s file, another %d tries"
                  % (f_name, tries_left)
              )
              PathManager.rm(f_name)
              tries_left -= 1
      print(
          "tokenizing and selecting %s %2f" % (f_name, time() - st_time)
      )
      processed_items = dict([(name, []) for name in subreddit_names])
      if mode == "submissions":
          key_list = ["id", "score", "url", "title", "selftext"]
      else:
          key_list = ["id", "link_id", "parent_id", "score", "body"]
      for name in subreddit_names:
          for line in lines[name]:
              reddit_dct = json.loads(line)
              if (
                  reddit_dct.get("num_comments", 1) > 0
                  and reddit_dct.get("score", 0)
                  and reddit_dct.get("score", 0) >= 2
                  and (
                      mode == "submissions" or valid_comment(reddit_dct)
                  )
              ):
                  reddit_res = {}
                  for k in key_list:
                      if k in ["title", "selftext", "body"]:
                          if reddit_dct[k].lower() in [
                              "[removed]",
                              "[deleted]",
                          ]:
                              reddit_dct[k] = ""
                          txt, url_list = word_url_tokenize(
                              reddit_dct[k]
                          )
                          reddit_res[k] = (
                              " ".join(txt.split()),
                              url_list,
                          )
                      else:
                          reddit_res[k] = reddit_dct[k]
                  processed_items[name] += [reddit_res]
      print("Total found %d" % (len(processed_items)), time() - st_time)
      return processed_items
  
imports: import bz2
  import io
  import json
  import lzma
  import re
  import requests
  import subprocess
  import zstandard
  from bs4 import BeautifulSoup
  from os.path import isfile
  from os.path import join
  from time import sleep, time
  from collections import defaultdict
  from parlai.core.params import ParlaiParser
  from data_utils import word_url_tokenize
  from parlai.utils.io import PathManager
label_desc: Use image node_id 3 for calling a global function with example usage: download_and_process(file_url, mode, subreddit_names, st_time, output_dir) and returns: processed_items