isFalsyLiteral = expr => {
	switch (expr.type) {
		case "Literal":
			return !expr.value;
		case "UnaryExpression":
			if (expr.operator === "!") return isTruthyLiteral(expr.argument);
	}
	return false;
}
The purpose of this function is to check whether an expression is a falsy literal or not. This is
useful when parsing CommonJS exports, because CommonJS modules can export any value, including falsy
values like `null` and `false`. However, exports should only be created if the exported value is truthy.
@param {Expression} expr expression being checked
@returns {boolean} true, when the expression is a falsy literal