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  1. import re
  2. s = r"#s{o}me\%thing $ \text{a} $"
  3. rx = r'(?<!\\)((?:\\{2})*)(?:(\$[^$\\]*(?:\\.[^$\\]*)*\$)|([%#{}&]))'
  4. print ( re.sub(rx, lambda x: fr"{x.group(1)}\{x.group(3)}" if x.group(3) else fr"{x.group(1)}{x.group(2)}", s, flags=re.S) )
Success #stdin #stdout 0.02s 9564KB
comments (?)
stdin 
Standard input is empty
stdout 
\#s\{o\}me\%thing $ \text{a} $
https://ideone.com/m2Dsgz
language:
Python 3 (python  3.12)
created:
6 years ago
visibility:
secret

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