foo = 'bar'
a = 4
bar-baz = 5
a += 8
url = "http://example.com"	// comment

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

[
	["variable-declaration", [
		["variable", "foo"],
		["operator", "="],
		["string", "'bar'"]
	]],
	["variable-declaration", [
		["variable", "a"],
		["operator", "="],
		["number", "4"]
	]],
	["variable-declaration", [
		["variable", "bar-baz"],
		["operator", "="],
		["number", "5"]
	]],
	["variable-declaration", [
		["variable", "a"],
		["operator", "+="],
		["number", "8"]
	]],
	["variable-declaration", [
		["variable", "url"],
		["operator", "="],
		["string", "\"http://example.com\""],
		["comment", "// comment"]
	]]
]

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

Checks for variable declarations.