$f
$foo
$foobar_42
$$bar
${$foo}

----------------------------------------------------

[
	["variable", "$f"],
	["variable", "$foo"],
	["variable", "$foobar_42"],
	["variable", "$$bar"],
	["variable", "$"], ["punctuation", "{"], ["variable", "$foo"], ["punctuation", "}"]
]

----------------------------------------------------

Checks for variables.