code: def _head_object(s3_conn, bucket, key):
      
      try:
          return s3_conn.head_object(Bucket=bucket, Key=key)
      except botocore.exceptions.ClientError as e:
          if e.response['Error']['Code'] == '404':
              return None
          else:
              raise
docs: Retrieve information about an object in S3 if it exists.
  
      Args:
          s3_conn (botocore.client.S3): S3 connection to use for operations.
          bucket (str): name of the bucket containing the key.
          key (str): name of the key to lookup.
  
      Returns:
          dict: S3 object information, or None if the object does not exist.
              See the AWS documentation for explanation of the contents.
  
      Raises:
          botocore.exceptions.ClientError: any error from boto3 other than key
              not found is passed through.