Reviewable now defaults to the Lodash 4.x module when executing new custom completion code. We'll continue using Lodash 3.x for existing conditions, but if you want to upgrade please add a dependencies directive anywhere in your condition:
// dependencies: lodash4
If you'd prefer to continue using Lodash 3.x for your existing conditions, no updates or flags are necessary.
You can confirm which Lodash version your condition is using here:
If there are any other dependencies you'd like to be able to use when executing your conditions, let us know and we'll do our best to support them!