code: function getPluralCategory(value, cases, ngLocalization, locale) {
      var /** @type {?} */ key = "=" + value;
      if (cases.indexOf(key) > -1) {
          return key;
      }
      key = ngLocalization.getPluralCategory(value, locale);
      if (cases.indexOf(key) > -1) {
          return key;
      }
      if (cases.indexOf('other') > -1) {
          return 'other';
      }
      throw new Error("No plural message found for value \"" + value + "\"");
  }
docs: Returns the plural category for a given value.
  - "=value" when the case exists,
  - the plural category otherwise
  
  \@internal
  @param {?} value
  @param {?} cases
  @param {?} ngLocalization
  @param {?=} locale
  @return {?}