diff --git a/src/ifcopenshell-python/ifcopenshell/express/schema_class.py b/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
index dc399b53d0..3981dbc421 100644
--- a/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
+++ b/src/ifcopenshell-python/ifcopenshell/express/schema_class.py
@@ -420,13 +420,15 @@ class SchemaClass(codegen.Base):
 
             if isinstance(type, nodes.AggregationType):
                 aggr_type = type.aggregate_type
+
                 def make_bound(b):
                     # `?` and non-literal bounds (attribute references, arithmetic expressions) collapse to -1.
-                    # 
+                    #
                     try:
                         return int(b)
                     except (TypeError, ValueError):
                         return -1
+
                 bound1, bound2 = map(make_bound, (type.bounds.lower, type.bounds.upper))
                 decl_type = get_declared_type(type.type, emitted_names)
                 return x.aggregation_type(aggr_type, bound1, bound2, decl_type)
@@ -553,6 +555,7 @@ class SchemaClass(codegen.Base):
                 inv_attrs = []
                 for attr in type.inverse:
                     if attr.bounds:
+
                         def make_bound(b):
                             # `?` and non-literal bounds (attribute references, arithmetic
                             # expressions) collapse to -1 (unbounded) — the C++ runtime has
@@ -561,6 +564,7 @@ class SchemaClass(codegen.Base):
                                 return int(b)
                             except (TypeError, ValueError):
                                 return -1
+
                         bound1, bound2 = map(make_bound, (attr.bounds.lower, attr.bounds.upper))
                     else:
                         bound1, bound2 = -1, -1
diff --git a/src/ifcopenshell-python/test/test_express_aggregate_bounds.py b/src/ifcopenshell-python/test/test_express_aggregate_bounds.py
index 030c301a78..24b81fda5b 100644
--- a/src/ifcopenshell-python/test/test_express_aggregate_bounds.py
+++ b/src/ifcopenshell-python/test/test_express_aggregate_bounds.py
@@ -24,9 +24,7 @@ def _parse(schema_text):
 class TestAggregateBounds(unittest.TestCase):
     def test_literal_bounds_preserved(self):
         """After loading [1;3] -> (1, 3)?"""
-        s = _parse(
-            "SCHEMA t; ENTITY E; v : ARRAY [1:3] OF REAL; END_ENTITY; END_SCHEMA;"
-        )
+        s = _parse("SCHEMA t; ENTITY E; v : ARRAY [1:3] OF REAL; END_ENTITY; END_SCHEMA;")
         agg = (
             next(d for d in s.schema.declarations() if d.name() == "E")
             .attributes()[0]
@@ -37,10 +35,8 @@ class TestAggregateBounds(unittest.TestCase):
         s.disown()
 
     def test_unbounded_marker(self):
-        """ [0:?] -> (0, -1)?"""
-        s = _parse(
-            "SCHEMA t; ENTITY E; v : LIST [0:?] OF REAL; END_ENTITY; END_SCHEMA;"
-        )
+        """[0:?] -> (0, -1)?"""
+        s = _parse("SCHEMA t; ENTITY E; v : LIST [0:?] OF REAL; END_ENTITY; END_SCHEMA;")
         agg = (
             next(d for d in s.schema.declarations() if d.name() == "E")
             .attributes()[0]
@@ -52,12 +48,11 @@ class TestAggregateBounds(unittest.TestCase):
         s.disown()
 
     def test_voxel_grid_with_dynamic_bound_loads(self):
-        """ 
+        """
         Array that is an expression :  [1:dim_x*dim_y*dim_z]
         Parsing must not crash, Bbund must be (1, -1)
         """
-        s = _parse(
-            """
+        s = _parse("""
             SCHEMA t;
             TYPE IfcBoolean = BOOLEAN; END_TYPE;
 
@@ -68,8 +63,7 @@ class TestAggregateBounds(unittest.TestCase):
               Voxels : ARRAY [1:NumberOfVoxelsX*NumberOfVoxelsY*NumberOfVoxelsZ] OF IfcBoolean;
             END_ENTITY;
             END_SCHEMA;
-            """
-        )
+            """)
         holder = next(d for d in s.schema.declarations() if d.name() == "IfcVoxelHolder")
         voxels = holder.attributes()[-1].type_of_attribute().as_aggregation_type()
         self.assertEqual((voxels.bound1(), voxels.bound2()), (1, -1))