diff --git a/mNSF/process_multiSample.py b/mNSF/process_multiSample.py
index 18f06d0..fc7de81 100644
--- a/mNSF/process_multiSample.py
+++ b/mNSF/process_multiSample.py
@@ -108,7 +108,7 @@ def get_D_fromAnnData(ad):
 	return D
 
 
-def get_listD_chunked(list_D_,list_nchunk=[1]*len(list_D_)):
+def get_listD_chunked(list_D_,list_nchunk=None):
 	"""
 	Prepare the training data by creating TensorFlow Datasets.
     
@@ -122,6 +122,7 @@ def get_listD_chunked(list_D_,list_nchunk=[1]*len(list_D_)):
     Returns:
     list_Dtrain: List of TensorFlow Datasets for training
 	"""
+	if(list_nchunk is None):list_nchunk=[1]*len(list_D_)
 	list_Dtrain=list()
 	nsample=len(list_D_)
 	# data chunking