docs: def detect_best_flux_limit(model):
      """Detect the best default flux limit to use for model output.
  
      The default flux limit does not change the model but selecting a good
      value reduced the amount of output produced and reduces clutter in the
      output files.
      """
      flux_limit_count = Counter()
  
      for reaction in model.reactions:
          if reaction.id not in model.limits:
              continue
  
          equation = reaction.properties['equation']
          if equation is None:
              continue
  
          _, lower, upper = model.limits[reaction.id]
          if upper is not None and upper > 0 and equation.direction.forward:
              flux_limit_count[upper] += 1
          if lower is not None and -lower > 0 and equation.direction.reverse:
              flux_limit_count[-lower] += 1
  
      if len(flux_limit_count) == 0:
          return None
  
      best_flux_limit, _ = flux_limit_count.most_common(1)[0]
      return best_flux_limit