`${`a string`}`

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

[
	["template-string", [
		["string", "`"],
		["interpolation", [
			["interpolation-punctuation", "${"],
			["template-string", [
				["string", "`a string`"]
			]],
			["interpolation-punctuation", "}"]
		]],
		["string", "`"]
	]]
]

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

Checks for nested template strings. See #1397