@("FOO")
	bar
	$baz
FOO

@(FOO BAR/)
	bar
	$baz
	| FOO BAR

@(foo!)
bar
|-foo!

@("some text..."/nrts$uL)
some text
some text..
some text...

$foo = @(FOOBAR) == $bar
	Foobar
	-FOOBAR

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

[
	["heredoc", ["@(", ["punctuation", "\"FOO\""], ")"]],
	["heredoc", [
		"\tbar\r\n\t",
		["interpolation", ["$baz"]],
		["punctuation", "FOO"]
	]],
	["heredoc", ["@(", ["punctuation", "FOO BAR/"], ")"]],
	["heredoc", [
		"\tbar\r\n\t$baz\r\n\t",
		["punctuation", "| FOO BAR"]
	]],
	["heredoc", ["@(", ["punctuation", "foo!"], ")"]],
	["heredoc", ["bar\r\n", ["punctuation", "|-foo!"]]],
	["heredoc", ["@(", ["punctuation", "\"some text...\"/nrts$uL"], ")"]],
	["heredoc", ["some text\r\nsome text..\r\n", ["punctuation", "some text..."]]],
	["variable", ["$foo"]], ["operator", "="],
	["heredoc", ["@(", ["punctuation", "FOOBAR"], ")"]],
	["operator", "=="], ["variable", ["$bar"]],
	["heredoc", ["\tFoobar\r\n\t", ["punctuation", "-FOOBAR"]]]
]

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

Checks for heredoc strings.
Also checks that string interpolation applies only inside quoted heredoc strings.