Regular expressions are represented by the Regex class, which is usually created with a literal:
foo_or_bar = /foo|bar/ heeello = /h(e+)llo/ integer = /\d+/
A regular expression literal is delimited by / and uses PCRE syntax.
It can be followed by these modifiers:
For example
r = /foo/imx
Slashes must be escaped:
slash = /\//
An alternative syntax is provided:
r = %r(regex with slash: /)
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https://crystal-lang.org/docs/syntax_and_semantics/literals/regex.html