diff --git a/torchquantum/algorithm/qcbm.py b/torchquantum/algorithm/qcbm.py
index a5e426a3..c0b6e5e3 100644
--- a/torchquantum/algorithm/qcbm.py
+++ b/torchquantum/algorithm/qcbm.py
@@ -45,7 +45,7 @@ def k_expval(self, px, py):
     def forward(self, px, py):
         """
         Squared MMD loss.
-
+    Args:
         px: First probability distribution
         py: Second probability distribution