expand.py: tidy output processing

Author: mizar

expand.py

@@ -119,10 +119,8 @@ def output_file(filename):
             print(i, file=f)
     output_data = subprocess.run(["rustfmt", temp_file], check=True)
     with open(temp_file, 'r', encoding='utf-8', newline='') as f:
-        if output_path is None:
-            for line in f:
-                print(line, end="", file=sys.stdout)
-        else:
-            with open(output_path, 'w', encoding='utf-8', newline='') as wf:
-                for line in f:
-                    print(line, end="", file=wf)
+        wf = open(output_path, 'w', encoding='utf-8', newline='') if output_path is not None else sys.stdout
+        for line in f:
+            print(line, end='', file=wf)
+        if output_path is not None:
+            wf.close()