function CustomUserFunction() {

QTGMC()
last.QTGMC
last.QTGMC()

QTGMC
1func()
last.1func
last.1func()

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

[
	["keyword", "function"],
	["function", "CustomUserFunction"],
	["punctuation", "("],
	["punctuation", ")"],
	["punctuation", "{"],

	["function", "QTGMC"],
	["punctuation", "("],
	["punctuation", ")"],

	["variable", "last"],
	["punctuation", "."],
	["function", "QTGMC"],

	["variable", "last"],
	["punctuation", "."],
	["function", "QTGMC"],
	["punctuation", "("],
	["punctuation", ")"],

	"\r\n\r\nQTGMC\r\n1func",
	["punctuation", "("],
	["punctuation", ")"],

	["variable", "last"],
	["punctuation", "."],
	"1func\r\n",

	["variable", "last"],
	["punctuation", "."],
	"1func",
	["punctuation", "("],
	["punctuation", ")"]
]

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

Valid identifiers (starts with [a-zA-Z_]) proceeding a '.', preceeding a '(', or both are user/external functions.
User/external functions that don't match the above are technically valid but indistinguisable from variables.
