code: function _parseRule(rule) {
      var parameters = [];
  
      // The format for specifying validation rules and parameters follows an
      // easy {rule}:{parameters} formatting convention. For instance the
      // rule "Max:3" states that the value may only be three letters.
      if (rule.indexOf(':')) {
        var ruleInfo  = rule.split(':');
        parameters = _parseParameters(ruleInfo[0], ruleInfo[1]);
      }
  
      return { parameters: parameters, rule: ruleInfo[0]};
    }
docs: parse the rule
  
  @param {Array} rule
  
  @return {Object}