docs: function getCacheKey (args, methodMeta) {
      // get cache data from method meta data
      var cache = methodMeta.cache
      // if cache spec has a list of params specified then use these
      if (cache.keyParams) {
          args = _.pick(args, cache.keyParams)
      }
      // otherwise use everything except session
      else {
          // shallow clone args
          args = _.clone(args)
          // delete session from clone
          delete args.session
      }
      // generate hex id for arg data
      return stableId({
          args: args,
          method: methodMeta.signature,
      })
  }