docs: Fix coding style of Python scripts using YAPF (#2606)

docs/build_mantests.py

@@ -2,12 +2,12 @@
 import yaml
 
 with open("content/manual/manual.yml") as f:
-  manual = yaml.safe_load(f)
-  for section in manual.get('sections', []):
-    for entry in section.get('entries', []):
-      for example in entry.get('examples', []):
-        print(example.get('program', '').replace('\n', ' '))
-        print(example.get('input', ''))
-        for s in example.get('output', []):
-          print(s)
-        print('')
+    manual = yaml.safe_load(f)
+    for section in manual.get('sections', []):
+        for entry in section.get('entries', []):
+            for example in entry.get('examples', []):
+                print(example.get('program', '').replace('\n', ' '))
+                print(example.get('input', ''))
+                for s in example.get('output', []):
+                    print(s)
+                print('')