diff --git a/rl4co/models/zoo/ham/attention.py b/rl4co/models/zoo/ham/attention.py
index 4636b88d..0c4d593e 100644
--- a/rl4co/models/zoo/ham/attention.py
+++ b/rl4co/models/zoo/ham/attention.py
@@ -56,7 +56,8 @@ def forward(self, q, h=None, mask=None):
             q: queries (batch_size, n_query, input_dim)
             h: data (batch_size, graph_size, input_dim)
             mask: mask (batch_size, n_query, graph_size) or viewable as that (i.e. can be 2 dim if n_query == 1)
-            Mask should contain 1 if attention is not possible (i.e. mask is negative adjacency)
+            
+        Mask should contain 1 if attention is not possible (i.e. mask is negative adjacency)
         """
         if h is None:
             h = q  # compute self-attention