code: function mergeConstraints(env, oldConstraints, newConstraints) {
  	const res = {
  		min: Math.max(oldConstraints.min || 0, newConstraints.min || 0),
  		max: Math.min(
  			oldConstraints.max !== undefined ? oldConstraints.max : 2,
  			newConstraints.max !== undefined ? newConstraints.max : 2
  		),
  		force: oldConstraints.force || newConstraints.force,
  	};
  
  	if (res.min > res.max) {
  		// If oldConstraints.force is set, older constraints win
  		if (!oldConstraints.force) {
  			// let newConstraints win, but complain
  			if (newConstraints.max !== undefined && newConstraints.max > res.min) {
  				res.max = newConstraints.max;
  			} else if (newConstraints.min && newConstraints.min < res.min) {
  				res.min = newConstraints.min;
  			}
  		}
  		res.max = res.min;
  		env.log("info/html2wt", 'Incompatible constraints (merge):', res,
  			loggableConstraints(oldConstraints), loggableConstraints(newConstraints));
  	}
  
  	return res;
  }
docs: Merge two constraints.
  
  @private