Update numbers in the middle of a string
Question: I'm looking at diff-style output, but I need to update the line numbers. So I
see:

    
    
    *** 1,2 *****
    Actual line 1
    Actual line 2
    --- 1,2 -----
    Expected line 1
    Expected line 2
    

and in my results file, I'm at resline. So if resline=line 90, I'd want to
change the second "1,2" to "91,92".

In perl, I'd use the following on the line that begins "---"

    
    
    s/(\d+?)/($1+$resline)/eg
    

How should I do this in python?


Answer: You would use `re.sub` and pass in a callable instead of a string as the
replacement:

    
    
    import re
    re.sub(r'\d+?', lambda m: str(int(m.group(0))+resline), YOUR_STR)
    

