Fix deprecation warning in sigmoid

src/nets/util.py

@@ -2,13 +2,11 @@ import torch
 from torch.nn import functional
 
 def parse_functional(functional_config):
-    if functional_config is None:
-        return None
-    elif isinstance(functional_config, str):
+    if isinstance(functional_config, str):
         if functional_config == 'relu':
             return functional.relu
         elif functional_config == 'sigmoid':
-            return functional.sigmoid
+            return torch.sigmoid
         elif functional_config == 'softmax':
             return functional.softmax
-    
+    return None