diff --git a/src/ifcopenshell-python/ifcopenshell/util/system.py b/src/ifcopenshell-python/ifcopenshell/util/system.py
index 208979e584..bc25575367 100644
--- a/src/ifcopenshell-python/ifcopenshell/util/system.py
+++ b/src/ifcopenshell-python/ifcopenshell/util/system.py
@@ -17,6 +17,8 @@
 # along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
 
 
+import ifcopenshell.util
+
 group_types = {
     "IfcZone": ("IfcZone", "IfcSpace", "IfcSpatialZone"),
     "IfcBuiltSystem": (
@@ -82,35 +84,37 @@ def get_connected_port(port):
         return rel.RelatingPort
 
 
+# TODO: cover in tests
 def get_connected_to(element):
     results = []
     for port in ifcopenshell.util.system.get_ports(element):
         for relConnectsPort in port.ConnectedTo:
-            for disPort in [relConnectsPort.RelatedPort,relConnectsPort.RelatingPort]:
-                if hasattr(disPort,"Nests"):
+            for disPort in [relConnectsPort.RelatedPort, relConnectsPort.RelatingPort]:
+                if hasattr(disPort, "Nests"):
                     for relNest in disPort.Nests:
                         if relNest.RelatingObject != element:
                             results.append(relNest.RelatingObject)
                 # IFC2X3 only, deprecated in IFC4
-                elif hasattr(disPort,"ContainedIn"):
+                elif hasattr(disPort, "ContainedIn"):
                     for relConPortToElement in disPort.ContainedIn:
                         if relConPortToElement.RelatedElement != element:
                             results.append(relConPortToElement.RelatedElement)
-    return(results)
+    return results
 
 
+# TODO: cover in tests
 def get_connected_from(element):
     results = []
     for port in ifcopenshell.util.system.get_ports(element):
         for relConnectsPort in port.ConnectedFrom:
-            for disPort in [relConnectsPort.RelatedPort,relConnectsPort.RelatingPort]:
-                if hasattr(disPort,"Nests"):
+            for disPort in [relConnectsPort.RelatedPort, relConnectsPort.RelatingPort]:
+                if hasattr(disPort, "Nests"):
                     for relNest in disPort.Nests:
                         if relNest.RelatingObject != element:
                             results.append(relNest.RelatingObject)
                 # IFC2X3 only, deprecated in IFC4
-                elif hasattr(disPort,"ContainedIn"):
+                elif hasattr(disPort, "ContainedIn"):
                     for relConPortToElement in disPort.ContainedIn:
                         if relConPortToElement.RelatedElement != element:
                             results.append(relConPortToElement.RelatedElement)
-    return(results)
\ No newline at end of file
+    return results