code: function(projectConfig, experimentKey, variationKey) {
      var experiment = projectConfig.experimentKeyMap[experimentKey];
      if (experiment.variationKeyMap.hasOwnProperty(variationKey)) {
        return experiment.variationKeyMap[variationKey].id;
      }
      return null;
    }
docs: Get the variation ID given the experiment key and variation key
  @param  {Object} projectConfig Object representing project configuration
  @param  {string} experimentKey Key of the experiment the variation belongs to
  @param  {string} variationKey  The variation key
  @return {string} the variation ID