code: def is_snapshot_time(self, output_every=None, t_output_every=None):
          
          if t_output_every is not None:
              output_every = int(round(t_output_every // self.model.dt))
          return not self.model.i % output_every
docs: Determine whether or not the model's iteration number is one
          where the runner is expected to make an output snapshot.