fork(1) download
  1. import re
  2.  
  3. pattern = r"X0+(?=X)"
  4. s = "001000X00X001X00X"
  5.  
  6. print(re.sub(pattern, lambda x: x.group().replace('0', '2'), s))
Success #stdin #stdout 0.02s 9324KB
stdin
Standard input is empty
stdout
001000X22X001X22X