text: function cleanProjection(conf = {}){
      const projectionConfg = {};
      for (let k in conf) {
          if (conf.hasOwnProperty(k) && conf[k]) {
              projectionConfg[k] = conf[k];
          }
      }
  
      return projectionConfg;
  }
  
  
  module.exports = {
      cleanProjection
  };