code: func doesBindingRuleMatch(rule *structs.ACLBindingRule, selectableVars interface{}) bool {
  	if rule.Selector == "" {
  		return true // catch-all
  	}
  
  	eval, err := bexpr.CreateEvaluatorForType(rule.Selector, nil, selectableVars)
  	if err != nil {
  		return false // fails to match if selector is invalid
  	}
  
  	result, err := eval.Evaluate(selectableVars)
  	if err != nil {
  		return false // fails to match if evaluation fails
  	}
  
  	return result
  }
docs: // doesBindingRuleMatch checks that a single binding rule matches the provided
  // vars.