function isRequiredParameter(node) {
	return !(
		node.type === "AssignmentPattern" ||
		node.type === "RestElement" ||
		node.optional
	);
}
Checks if node is required: i.e. does not have a default value or ? optional indicator.
@param {ASTNode} node the node to be evaluated
@returns {boolean} true if the node is required, false if not.