Added UPB simple resource model and corresponding tests. Closes #12
diff --git a/src/emuvim/dcemulator/node.py b/src/emuvim/dcemulator/node.py
index 9ccdb7f..8de3ae7 100755
--- a/src/emuvim/dcemulator/node.py
+++ b/src/emuvim/dcemulator/node.py
@@ -192,6 +192,11 @@
         }
 
     def assignResourceModel(self, rm):
+        """
+        Assign a resource model to this DC.
+        :param rm: a BaseResourceModel object
+        :return:
+        """
         if self._resource_model is not None:
             raise Exception("There is already an resource model assigned to this DC.")
         self._resource_model = rm