Kelas Karakter di Regex

//Character classes are one of the primary means of “grouping” characters 
//in a regex pattern without necessarily enforcing an order to those characters.

[abc]	Includes any of the contained characters
[^abc]	Excludes all of the contained characters
[a-z]	Includes any of the contained characters across a range
.	    Any character except newline
\w	    Any word character (alphanumeric and underscore)
\d	    Any digit [0-9]
\s	    Whitespace (spaces, tabs, line breaks)
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