[Python]Regular Expression Syntax

Element	Meaning
.	Matches any character except /n(if DOTALL, also matches /n)
^	Matches start of string(if MULTILINE, also matches after /n)
$	Matches end of string(if MULTILINE, also matches before /n)
*	Matches zero or more cases of the previous RE; greedy(match as many as possible)
+	Matches one or more cases of the previous RE; greedy(match as many as possible)
?	Matches zero or one case of the previous RE; greedy(match one if possible)
*?, +?, ??	Nongreedy versions of *, + and ?(match as few as possible)
{m,n}	Matches m to n cases of the previous RE(greedy)
{m,n}?	Matches m to n cases of the previous RE(nongreedy)
[...]	Matches any one of a set of characters contained within the brackets
|	Matches either preceding expression or following expression
(...)	Matches the RE within the parentheses and indicates a group
(?iLmsux)	Alternate way to set optional flags; no errect on match
(?:...)	Like (...), but does not indicate a group
(?P<id>...)	Like (...), but the group also gets the name id
(?P=id)	Matches whatever was previously matched by group named id
(?#...)	Content of parentheses is just a comment; no effect on match
(?=...)	Lookahead assertion: matches if RE ... matches what comes next, but does not consume any part of the string
(?!...)	Negative lookahead assertion: matches if RE ... does not match waht comes next, and does not consume any part of the string
(?<=...)	Lookbehind assertion: matches if there is a match ending at the current position for RE ... (... must match a fixed length)
(?<!...)	Negative lookbehind assertion: matches if there is no match ending at the current position for RE ... (... must match a fixed length)
/number	Matches whatever was previously matched by group numbered number(groups are automatically numbered from 1 to 99)
/A	Matches an empty string, but only at the start of the whole string
/b	Matches an empty string but only at the start or end of a word(a maximal sequence of alphanumeric characters; see also /w)
/B	Matches an empty string, but not at the start or end of a word
/d	Matches one digit, like the set [0-9]
/D	Matches one non digit, like the set [^0-9]
/s	Matches a whitespace character, like the set [/t/n/r/f/v]
/S	Matches a non whitespace character, like the set [^/t/n/r/f/v]
/w	Matches one alphanumeric character; unless LOCALE or UNICODE is set, /w is like [a-zA-Z0-9_]
/W	Matches one non alphanumeric character, the reverse of /w
/Z	Matches an empty string, but only at the end of the whole string
//	Matches one backslash character