Regular Expressions 101

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"
(&[lmnok])(.*?)(&r|$)
"
gm
1st Capturing Group
(&[lmnok])
& matches the character & with index 3810 (2616 or 468) literally (case sensitive)
Match a single character present in the list below
[lmnok]
lmnok
matches a single character in the list lmnok (case sensitive)
2nd Capturing Group
(.*?)
.
matches any character (except for line terminators)
*? matches the previous token between zero and unlimited times, as few times as possible, expanding as needed (lazy)
3rd Capturing Group
(&r|$)
1st Alternative
&r
&r
matches the characters &r literally (case sensitive)
2nd Alternative
$
$ asserts position at the end of a line
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)
Your regular expression does not match the subject string.

Regular Expression
No Match

r"
"
gm

Test String