import re
rx_R = r'(?:\u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029])'
s = "Line1.\r\nLine2.\rLine3.\nLine4\r\nLine5"
res = re.sub(r'(\.{0})|{0}'.format(rx_R), lambda x: x.group(1) if x.group(1) else '', s)
print(res)
print(res.replace("\n", "LF").replace("\r", "CR"))
aW1wb3J0IHJlCnJ4X1IgPSByJyg/Olx1MDAwRFx1MDAwQXxbXHUwMDBBXHUwMDBCXHUwMDBDXHUwMDBEXHUwMDg1XHUyMDI4XHUyMDI5XSknCnMgPSAiTGluZTEuXHJcbkxpbmUyLlxyTGluZTMuXG5MaW5lNFxyXG5MaW5lNSIKcmVzID0gcmUuc3ViKHInKFwuezB9KXx7MH0nLmZvcm1hdChyeF9SKSwgbGFtYmRhIHg6IHguZ3JvdXAoMSkgaWYgeC5ncm91cCgxKSBlbHNlICcnLCBzKQpwcmludChyZXMpCnByaW50KHJlcy5yZXBsYWNlKCJcbiIsICJMRiIpLnJlcGxhY2UoIlxyIiwgIkNSIikp