SageTeX Warning of Sagemath-9.0 on string with Escaped 'S'

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After I installed SageMath-9.0 (MacApplication), I encountered the following warning in the log of SageTeX compilation.

Console /Applications/SageMath-9.0.app/Contents/Resources/sage/local/lib/python3.7/site-packages/sagetex.py:63: DeprecationWarning: invalid escape sequence \S [re.match(' *\S', line) for line in lines]

I looked through the internet and found a similar situation in some other software.

• ThiefMaster
• "invalid escape sequence" DeprecationWarnings with Python 3.6 #646
• github.com/pallets/jinja/issues/646

I am trying the solution of this page on GitHub.

The relevant part is around line 63 of sagetex.py, which I quote here.

```python
def strip_common_leading_spaces(s):
    lines = s.splitlines()
    lead = min(m.end() for m in
                  [re.match(r' *\S', line) for line in lines]
                  if m is not None) - 1
    return '\n'.join(line[lead:] for line in lines)
```

As in this quotation, I just inserted the letter 'r' to the left of the string on line 63. It is the first line of the deepest indentation in this quotation.

Is this a good solution?