Python RegExp

Since Python 3.12 whe you use regular expression pattern you could get SyntaxWarning: invalid escape sequence '\-' error.

So this pattern will fail:

pattern='[^0-9a-zA-Z_\-\.]+'

This is because a backslash is only allowed when part of the valid escape sequence, like \n.

You should use raw strings by prefixing your string with r:

pattern=r'[^0-9a-zA-Z_\-\.]+'