code: function addParamGroups(command) {
    Object.defineProperty(command, 'paramGroups', {
      get: function() {
        var paramGroups = {};
        this.params.forEach(function(param) {
          var groupName = param.option || l10n.lookup('canonDefaultGroupName');
          if (paramGroups[groupName] == null) {
            paramGroups[groupName] = [];
          }
          paramGroups[groupName].push(param);
        });
        return paramGroups;
      },
      enumerable: true
    });
  }
docs: Add an 'paramGroups' accessor to a command metadata object to sort the
  params into groups according to the option of the param.