new_contents: import warnings
  import sys
  import argparse
  
  from etk.extractors.date_extractor import DateExtractor
  
  date_extractor = DateExtractor()
  
  
  def add_arguments(parser):
      """
      Parse arguments
      Args:
          parser (argparse.ArgumentParser)
      """
      parser.description = 'Examples:\n' \
                           'python -m etk date_extractor /tmp/date.txt\n' \
                           'cat /tmp/date.txt | python -m etk date_extractor'
      parser.add_argument('input_file', nargs='?', type=argparse.FileType('r'), default=sys.stdin)
  
  
  def run(args):
      """
      Args:
          args (argparse.Namespace)
      """
      with warnings.catch_warnings():
          warnings.simplefilter('ignore')
  
          for line in args.input_file:
              extractions = date_extractor.extract(line)
              for e in extractions:
                  print(e.value)
  
subject: add basic cli of date_extractor