diff --git a/threefive/descriptors.py b/threefive/descriptors.py
index 2687e3ba..8636b0bf 100644
--- a/threefive/descriptors.py
+++ b/threefive/descriptors.py
@@ -281,9 +281,9 @@ def xml(self):
         td = Node(
             "TimeDescriptor",
             attrs={
-                "tai_seconds":self.tai_seconds,
-                "tai_ns":self.tai_ns,
-                "utc_offset":self.utc_offset,
+                "tai_seconds": self.tai_seconds,
+                "tai_ns": self.tai_ns,
+                "utc_offset": self.utc_offset,
             },
         )
         return td
@@ -486,7 +486,7 @@ def xml(self):
                 self.segmentation_duration
             )
         sd = Node("SegmentationDescriptor", attrs=sd_attrs)
-       # sd.add_comment(f'{table22[self.segmentation_type_id]}') # Called in cue.py
+        # sd.add_comment(f'{table22[self.segmentation_type_id]}') # Called in cue.py
         the_upid = self.mk_the_upid()
         the_upid.upid_value = self.segmentation_upid
         upid_node = the_upid.xml()
@@ -504,7 +504,7 @@ def xml(self):
                     },
                 )
             )
-        sd.add_comment(f'UPID: {upid_map[self.segmentation_upid_type][0]}')
+        sd.add_comment(f"UPID: {upid_map[self.segmentation_upid_type][0]}")
 
         if isinstance(upid_node, list):
             for node in upid_node:
@@ -534,7 +534,7 @@ def from_xml(self, stuff):
             self.segmentation_upid_type = 0
             if "SegmentationUpid" in stuff:
                 self.load(stuff["SegmentationUpid"])
-              #  self.segmentation_upid_length = len(self.segmentation_upid.strip("0x"))
+            #  self.segmentation_upid_length = len(self.segmentation_upid.strip("0x"))
             self._chk_sub_segments()