code: function checkByRule ( ruleInfo, value, fieldMeta ) {
          var rule    = ruleInfo.rule
            , isValid = VALIDATORS[ rule ];
  
          checkRuleExistence( isValid, rule );
          return isValid( ruleInfo, value, fieldMeta ) ? null : ruleInfo;
      }
docs: Validates field's value against of validation rule.
  Returs sublist of validateion rules that was not sutisfied
  by value.
  @param {Object} ruleInfo - validation rules.
  @param {Object} value - value to validate.
  @param {Object} fieldMeta - for some validation rules
  field meta is required.
  @returns {Object}