Determines whether a path exists or not.

def exists(self, filename):
        """Determines whether a path exists or not."""
        client = boto3.client("s3")
        bucket, path = self.bucket_and_path(filename)
        r = client.list_objects(Bucket=bucket, Prefix=path, Delimiter="/")
        if r.get("Contents") or r.get("CommonPrefixes"):
            return True
        return False