code: function requireAssets( requireFile, assetPaths, assetUrlPaths ) {
     return function( assets ) {
        return Promise.all( Object.keys( assets ).map( key => {
           const asset = assets[ key ];
  
           if( ( assetPaths || [] ).indexOf( key ) >= 0 ) {
              return requireFile( asset, 'content' )
                 .then( content => ( { [ key ]: { content } } ) );
           }
  
           if( ( assetUrlPaths || [] ).indexOf( key ) >= 0 ) {
              return requireFile( asset, 'url' )
                 .then( url => ( { [ key ]: { url } } ) );
           }
  
           return {};
        } ) ).then( merge );
     };
  }
docs: ///////////////////////////////////////////////////////////////////////////////////////////////////////////