function isBoundary(node) {
	const t = node.type;

	return (
		t === "FunctionDeclaration" ||
		t === "FunctionExpression" ||
		t === "ArrowFunctionExpression" ||
		/*
		 * Don't report the await expressions on for-await-of loop since it's
		 * asynchronous iteration intentionally.
		 */
		(t === "ForOfStatement" && node.await === true)
	);
}
Check whether it should stop traversing ancestors at the given node.
@param {ASTNode} node A node to check.
@returns {boolean} `true` if it should stop traversing.