Escape sequences

move_html_to_dir

@@ -2,7 +2,6 @@
 """
 Rename files like `foo/bar.html` to `foo/bar/index.html` for prettier URLs.
 """
-import os
 import re
 import sys
 from pathlib import Path
@@ -20,7 +19,7 @@ def replace_links(path: Path, replacements: Dict[str, str]):
 
             # Convert absolute links to relative.
             contents = re.sub(
-                '((?:href|src|root)\s*=\s*")((?:\.\./)+)([^\.])', r"\1/\3", contents
+                r'((?:href|src|root)\s*=\s*")((?:\.\./)+)([^\.])', r"\1/\3", contents
             )
 
             f.write(contents)