Run black formatter on build.py

Author: dgerlanc

build.py

@@ -9,14 +9,15 @@
 # TODO: Only update files changed since last run
 # TODO: Add conversion tool from existing answer notebooks
 
+
 def answer2exercise(infile, outfile):
     """
     Convert answer notebooks to exercise notebooks
     
     TODO: Fail if output notebook is empty?
 
     """
-    cmd = 'jupyter nbconvert --config config.py --to notebook --output'.split()
+    cmd = "jupyter nbconvert --config config.py --to notebook --output".split()
     cmd.extend([outfile, infile])
     subprocess.run(cmd)
 
@@ -26,41 +27,43 @@ def slide2html(infile):
     Convert slide notebooks to reveal.js
 
     """
-    cmd = ('jupyter nbconvert'
-           ' --to slides'
-           ' --reveal-prefix=reveal.js'
-           ' --SlidesExporter.file_extension=.html'
-           ' --output-dir build').split()
+    cmd = (
+        "jupyter nbconvert"
+        " --to slides"
+        " --reveal-prefix=reveal.js"
+        " --SlidesExporter.file_extension=.html"
+        " --output-dir build"
+    ).split()
     cmd.append(str(infile))
     subprocess.run(cmd)
 
 
 def run_slide(infile):
-    cmd = 'jupyter nbconvert --to notebook --inplace --execute'.split()
+    cmd = "jupyter nbconvert --to notebook --inplace --execute".split()
     cmd.append(str(infile))
 
     devnull = subprocess.DEVNULL
     subprocess.run(cmd, check=True, stdout=devnull, stderr=devnull)
 
 
 def main():
-    p = Path('.')
+    p = Path(".")
 
     # TODO: add test for errors
-    slide_fns = p.glob('*slides.ipynb')
+    slide_fns = p.glob("*slides.ipynb")
     for slide_fn in sorted(slide_fns):
-        print(f'Running {slide_fn}')
+        print(f"Running {slide_fn}")
         run_slide(slide_fn)
 
-    print('ipynb slides -> reveal.js html')
-    slide_fns = p.glob('*slides.ipynb')
+    print("ipynb slides -> reveal.js html")
+    slide_fns = p.glob("*slides.ipynb")
     for slide_fn in sorted(slide_fns):
         slide2html(slide_fn)
-    
-    print('Convert answers to exercises')
-    answers = p.glob('*answers.ipynb')
+
+    print("Convert answers to exercises")
+    answers = p.glob("*answers.ipynb")
     for answer_nb in sorted(answers):
-        exercise_nb = str(answer_nb).replace('answer', 'exercise')
+        exercise_nb = str(answer_nb).replace("answer", "exercise")
         # print(f'{answer_nb} -> {exercise_nb}')
         answer2exercise(str(answer_nb), exercise_nb)
 
@@ -69,6 +72,5 @@ def main():
     # html slides -> pdf
 
 
-               
-if __name__ == '__main__':
+if __name__ == "__main__":
     main()