Operator Behavior
. Wildcard, matches any character
^abc Matches some pattern abc at the start of a string
abc$ Matches some pattern abc at the end of a string
[abc] Matches one of a set of characters
[A-Z0-9] Matches one of a range of characters
ed|ing|s Matches one of the specified strings (disjunction)
* Zero or more of previous item, e.g. a*, [a-z]* (also known as Kleene Closure)
+ One or more of previous item, e.g. a+, [a-z]+
? Zero or one of the previous item (i.e. optional), e.g. a?, [a-z]?
{n} Exactly n repeats where n is a non-negative integer
{n,} At least n repeats
{,n} No more than n repeats
{m,n} At least m and no more than n repeats
a(b|c)+ Parentheses that indicate the scope of the operators
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