code: function(aliasMap, config) {
      var aliases = this._flattenAliasMap(aliasMap);
      var allExcept = null;
  
      if (typeof config.allExcept !== 'undefined') {
        allExcept = this._castArray(config.allExcept);
        delete config.allExcept;
      }
  
      var keys = Object.keys(config);
  
      if (allExcept) {
        keys = keys.concat(allExcept);
      }
  
      var unknownConfigKeys = _.difference(keys, aliases);
  
      if (unknownConfigKeys.length) {
        this._logUnknownPlugins(unknownConfigKeys, 'config.pipeline.disabled');
      }
  
      var disabledMap = aliases.reduce(function(map, alias) {
        if (map[alias] === undefined) {
          if (allExcept && allExcept.length) {
            if (allExcept.indexOf(alias) >= 0) {
              map[alias] = false;
            } else {
              map[alias] = true;
            }
          } else {
            map[alias] = false;
          }
        }
  
        return map;
      }, config);
  
      return disabledMap;
    }
docs: Build up a hash of disabled plugin instances, keyed by alias, with the value being whether it's disabled or not
  This hash will contain an entry for every installed plugin.
  
  If a plugin has not been referenced in `config.pipeline.disabled` then it will be added to the map as `disabled: false`.
  
  Example return value:
  
  {
  foo: true,
  bar: false
  }