(( 4 + 5 ))
$((5 * 7))
"foo $((5 * 7)) bar"
for (( NUM=1 ; NUM<=1000 ; NUM++ ))

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

[
	["variable", [
		["punctuation", "(("],
		["number", "4"],
		["operator", "+"],
		["number", "5"],
		["punctuation", "))"]
	]],
	["variable", [
		["variable", "$(("],
		["number", "5"],
		["operator", "*"],
		["number", "7"],
		["variable", "))"]
	]],
	["string", [
		"\"foo ",
		["variable", [
			["variable", "$(("],
			["number", "5"],
			["operator", "*"],
			["number", "7"],
			["variable", "))"]
		]],
		" bar\""
	]],
	["keyword", "for"],
	["variable", [
		["punctuation", "(("],
		" NUM",
		["operator", "="],
		["number", "1"],
		["punctuation", ";"],
		" NUM",
		["operator", "<="],
		["number", "1000"],
		["punctuation", ";"],
		" NUM",
		["operator", "++"],
		["punctuation", "))"]
	]]
]

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

Checks arithmetic environments