diff --git a/pyfm/pylibfm.py b/pyfm/pylibfm.py
index b0b71a4..f04c634 100644
--- a/pyfm/pylibfm.py
+++ b/pyfm/pylibfm.py
@@ -2,7 +2,7 @@
 from sklearn.model_selection import train_test_split
 import random
 from pyfm_fast import FM_fast, CSRDataset
-
+from collections import defaultdict
 LEARNING_RATE_TYPES = {"optimal": 0, "invscaling": 1, "constant": 2}
 TASKS = {"regression": 0, "classification" : 1}
 
@@ -129,6 +129,8 @@ def _bool_to_int(self, bool_arg):
             return 1
         else:
             return 0
+    def fact(n):
+        return n*n
 
     def _prepare_y(self,y):
         """Maps labels to [-1, 1] space"""