code: def file_exists(original_file):
      
      s3 = boto3.resource('s3')
      bucket_name, object_key = _parse_s3_file(original_file)
      bucket = s3.Bucket(bucket_name)
      bucket_iterator = bucket.objects.filter(Prefix=object_key)
      bucket_list = [x for x in bucket_iterator]
      logger.debug("Bucket List: {0}".format(", ".join([x.key for x in bucket_list])))
      logger.debug("bucket_list length: {0}".format(len(bucket_list)))
      return len(bucket_list) == 1
docs: Validate the original file is in the S3 bucket