code: function getReducerObj (dataModel, reducers = {}) {
      const retObj = {};
      const fieldStore = dataModel.getFieldspace();
      const measures = fieldStore.getMeasure();
      const defReducer = reducerStore.defaultReducer();
  
      Object.keys(measures).forEach((measureName) => {
          if (typeof reducers[measureName] !== 'string') {
              reducers[measureName] = measures[measureName].defAggFn();
          }
          const reducerFn = reducerStore.resolve(reducers[measureName]);
          if (reducerFn) {
              retObj[measureName] = reducerFn;
          } else {
              retObj[measureName] = defReducer;
              reducers[measureName] = defaultReducerName;
          }
      });
      return retObj;
  }
docs: This sanitize the reducer provide by the user and create a common type of object.
  user can give function Also
  @param  {DataModel} dataModel     dataModel to worked on
  @param  {Object|function} [reducers={}] reducer provided by the users
  @return {Object}               object containing reducer function for every measure