Fix trailing commas

stix2/properties.py

@@ -170,8 +170,10 @@ class Property(object):
         self.required = required
 
         if required and default:
-            raise STIXError("Cant't use 'required' and 'default' together. 'required'"
-                            "really means 'the user must provide this.'")
+            raise STIXError(
+                "Cant't use 'required' and 'default' together. 'required'"
+                "really means 'the user must provide this.'",
+            )
 
         if fixed:
             self._fixed_value = fixed

stix2/test/v21/constants.py

@@ -131,7 +131,7 @@ MALWARE_ANALYSIS_KWARGS = dict(
 
 NOTE_KWARGS = dict(
     content="Heartbleed",
-    object_refs=[CAMPAIGN_ID]
+    object_refs=[CAMPAIGN_ID],
 )
 
 OBSERVED_DATA_KWARGS = dict(
@@ -148,7 +148,7 @@ OBSERVED_DATA_KWARGS = dict(
 
 OPINION_KWARGS = dict(
     opinion="agree",
-    object_refs=[CAMPAIGN_ID]
+    object_refs=[CAMPAIGN_ID],
 )
 
 REPORT_KWARGS = dict(