replace settings=None with {}

src/ifcopenshell-python/ifcopenshell/api/classification/add_classification.py

@@ -3,7 +3,7 @@ import ifcopenshell.util.schema
 import ifcopenshell.util.date
 
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "classification": None,

src/ifcopenshell-python/ifcopenshell/api/classification/add_reference.py

@@ -3,7 +3,7 @@ import ifcopenshell.util.schema
 
 
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "product": None,

src/ifcopenshell-python/ifcopenshell/api/classification/edit_classification.py

@@ -1,5 +1,5 @@
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "classification": None,

src/ifcopenshell-python/ifcopenshell/api/classification/edit_reference.py

@@ -1,5 +1,5 @@
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {
             "reference": None,

src/ifcopenshell-python/ifcopenshell/api/classification/remove_classification.py

@@ -1,5 +1,5 @@
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {"classification": None}
         for key, value in settings.items():

src/ifcopenshell-python/ifcopenshell/api/classification/remove_reference.py

@@ -2,7 +2,7 @@ import ifcopenshell.util.schema
 
 
 class Usecase:
-    def __init__(self, file, settings=None):
+    def __init__(self, file, settings={}):
         self.file = file
         self.settings = {"reference": None, "product": None}
         for key, value in settings.items():