From 86dc39a572207e5bd5b11bbca8018a2d3601093d Mon Sep 17 00:00:00 2001
From: cyyc1 <114281716+cyyc1@users.noreply.github.com>
Date: Wed, 5 Oct 2022 20:43:07 -0700
Subject: [PATCH] Add comments

---
 .../string_fixer_for_jupyter_notebooks.py           | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/pre_commit_hooks/string_fixer_for_jupyter_notebooks.py b/pre_commit_hooks/string_fixer_for_jupyter_notebooks.py
index 6f1de07..78854fd 100644
--- a/pre_commit_hooks/string_fixer_for_jupyter_notebooks.py
+++ b/pre_commit_hooks/string_fixer_for_jupyter_notebooks.py
@@ -14,19 +14,26 @@ def fix_strings(filename: str) -> int:
     cells = notebook_contents['cells']
     return_value = 0
     for cell in cells:
-        if cell['cell_type'] == 'code':
+        if cell.get('cell_type') == 'code' and 'source' in cell:
+            # Each element in cell['source'] is a string that ends with \n,
+            # except for the last element, which is why we don't join by \n
             source_in_1_line = ''.join(cell['source'])
             fixed = fix_strings_in_file_contents(source_in_1_line)
             if fixed != source_in_1_line:
                 fixed_lines = fixed.split('\n')
-                cell['source'] = [_ + '\n' for _ in fixed_lines[:-1]] + [fixed_lines[-1]]
+                cell['source'] = (
+                        [_ + '\n' for _ in fixed_lines[:-1]]
+                        + [fixed_lines[-1]]
+                )
                 return_value = 1
 
     if return_value == 1:
         notebook_contents['cells'] = cells
         with open(filename, 'w') as f:
             json.dump(notebook_contents, f, indent=1)
-            f.write("\n")  # because json.dump doesn't put \n at the end
+            # Jupyter notebooks (.ipynb) always ends with a new line
+            # but json.dump does not.
+            f.write("\n")
 
     return return_value