code: function globalReset (self) {
      // reset data for all instances
      _.each(global.__immutable_global__, instance => instance.reset())
      // reset internal data
      if (self) {
          global.__immutable_global__ = {}
      }
  }
docs: @function resetData
  
  reset global data for all instances. if the self flag is set the internal
  register will be reset as well (used for testing).
  
  @param {boolean} self