code: function( sites, pluginSlug ) {
  		let plugin,
  			plugins = this.getPlugins( sites ),
  			pluginSites;
  		if ( ! plugins ) {
  			return;
  		}
  
  		plugin = find( plugins, _filters.isEqual.bind( this, pluginSlug ) );
  		if ( ! plugin ) {
  			return null;
  		}
  
  		pluginSites = plugin.sites
  			.filter( site => site.visible )
  			.map( site => {
  				// clone the site object before adding a new property. Don't modify the return value of getSite
  				const pluginSite = clone( getSite( reduxGetState(), site.ID ) );
  				pluginSite.plugin = site.plugin;
  				return pluginSite;
  			} );
  
  		return pluginSites.sort( function( first, second ) {
  			return first.title.toLowerCase() > second.title.toLowerCase() ? 1 : -1;
  		} );
  	}
docs: Array of sites with a particular plugin.