Regular Expressions 101

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"
.{1,}?([。.」??!!]+|\n)
"
gmiu
.
matches any character, including unicode (except for line terminators)
{1,}? matches the previous token between one and unlimited times, as few times as possible, expanding as needed (lazy)
1st Capturing Group
([。.」??!!]+|\n)
1st Alternative
[。.」??!!]+
Match a single character present in the list below
[。.」??!!]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
。.」??!!
matches a single character in the list 。.」??!! (case insensitive)
2nd Alternative
\n
\n matches a line-feed (newline) character (ASCII 10)
Global pattern flags
g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)
i modifier: insensitive. Case insensitive match (ignores case of [a-zA-Z])
u modifier: unicode. Make \w, \W, \b, \B, \d, \D, \s and \S perform matching with Unicode semantic (redundant in Python 3)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
gmiu

Test String