Notes contain non-visible characters

There are three non-visible characters (\x7f, \x14, and \x13) that appear in the notes. These characters cause issues when working with many text processing tools. Removing these characters will make it easier to work with the notes and should not change the underlying meaning.

Currently, when using processing tools (e.g., cTAKES) that process a directory, one can workaround this issue by manually removing the offending characters:

find notes -type f -exec sed -i 's/\x7f//g; s/\x14//g; s/\x13//g' {} +

These characters appear in ~700 notes. A truncated character distribution shows:

[ # ...
 ('\x13', 677),
 ('\x14', 49),
 ('\x7f', 2)]

There does not appear to be overlap among the affected notes.

find notes -type f | xargs grep --color='auto' -P -l "[\x7f]" | sort | uniq -c
      1 notes/1062359
      1 notes/862440

find notes -type f | xargs grep --color='auto' -P -l "[\x14]" | sort | uniq -c
      1 notes/1437693
      1 notes/1482241
...

find notes -type f | xargs grep --color='auto' -P -l "[\x13]" | sort | uniq -c
      1 notes/1901399
      1 notes/1902291
...

Start by reviewing the affected files under notes/ and the provided find, grep, and sed commands. Verify that \x7f, \x14, and \x13 are removed from the affected notes without changing other content, and confirm the notes can be processed without the manual workaround.