text: const deriveEvt = require('../../common/transformation');
  
  module.exports = function createContextOperators(cepjsRx) {
    const { map } = cepjsRx.lib.operators;
  
    const operators = {};
  
    /**
    * 
    * @param {string[]} attributeList
    * @param {string} newEventTypeId
    * @return {Observable} a new event stream instance.
    */
    operators.project = (attributeList, newEventTypeId) => stream =>
      stream.pipe(map(deriveEvt(attributeList, newEventTypeId)));
  
    return operators;
  }