function isLabeledBy(node, labelName) {
        for (var owner = node.parent; owner.kind === 207 /* LabeledStatement */; owner = owner.parent) {
            if (owner.label.text === labelName) {
                return true;
            }
        }
        return false;
    }
Whether or not a 'node' is preceded by a label of the given string.
Note: 'node' cannot be a SourceFile.