Fix: Python replace unprintable characters except linebreak

 To replace unprintable characters in a Python string with the exception of line breaks, you can use regular expressions to match and replace non-printable characters. Here's an example of how you can do this:

```python

import re

def replace_unprintable_except_linebreak(input_string):

    # Define a regular expression pattern to match non-printable characters except line breaks

    pattern = r'[^\x09\x0A\x0D\x20-\x7E]'

    # Use re.sub to replace matched characters with an empty string

    cleaned_string = re.sub(pattern, '', input_string)

    return cleaned_string

# Example usage:

input_text = "Hello, this is a\x07sample text with\x0Bunprintable\x08characters.\nBut line breaks are fine."

cleaned_text = replace_unprintable_except_linebreak(input_text)

print(cleaned_text)

```

In this code:

1. We define a regular expression pattern `r'[^\x09\x0A\x0D\x20-\x7E]'`, which matches any character that is not a tab (0x09), line feed (0x0A), carriage return (0x0D), or a printable ASCII character in the range 0x20 to 0x7E.

2. We use `re.sub` to replace all characters matching the pattern with an empty string, effectively removing them.

3. The example demonstrates how to use the function on an input text, preserving line breaks while removing other unprintable characters.

The result of this code will be a cleaned string with unprintable characters removed except for line breaks.