code: function streamParticles(duration) {
           this._enabled = true;
           this._stream = true;
           this.frequency = Math.max(this.frequency, 1);
           this._durationTimer = typeof duration === "number" ? duration : this.duration;
         }
docs: Launch particles from emitter constantly <br>
  Particles example: Fountains
  @param {Number} duration [optional] time that the emitter releases particles in ms
  @function
  @name streamParticles
  @memberOf me.ParticleEmitter