Helping Huad understand how to use Python to remove accidentally repeated chars from a file

remove_bad_str.py

# re is the regular expressions library
# which facilitates our search for, and 
# replacement of, strings!
import re

# This is the string we want to remove
bad_text = '#'

# Regular expressions are too deep to explain here.
# Look up a tutorial on regexes if you're curious!
bad_text_regex = re.compile(bad_text + '+')

# We only remove it if it's repeated lots of times
# (afterall, there may be other parts of the program
# where we want this text to still appear!)
bad_text_repetition_limit = 5

bad_file_name = 'code.py'

# r+ means we can read and write to the file
# (if we left this out, we'd only be able to read)
# Learn more about modes here: 
# https://docs.python.org/3/library/functions.html#open
file_mode = 'r+'

with open(bad_file_name, file_mode) as bad_file:
    bad_file_contents = bad_file.read()

    bad_text_matches = bad_text_regex.findall(bad_file_contents)

    problematic_matches = set(
        match 
        for match in bad_text_matches 
        if len(match) >= bad_text_repetition_limit
    )

    fixed_contents = bad_file_contents

    for match in problematic_matches:
        print(match)
        fixed_contents = fixed_contents.replace(match, '')

    # Now we're ready to write the fixed contents to the file.
    # But since we read the file, now we're at the end of it, 
    # so we have to go back to the beginning using .seek()
    bad_file.seek(0)

    bad_file.write(fixed_contents)

    # Since we've made the contents smaller,
    # We need to truncate the file to the new,
    # smaller size!
    bad_file.truncate()