usage: example_index <files>
  -h, --help             Show this help message
  -s, --server           StanfordNLP server URI (default is https://localhost:9000)
  -l, --lang             Language to use (default is fr)
  -w, --whitelist-exts   Allowed file extensions (default is [])
  -b, --blacklist-exts   Allowed file extensions (default is [])