lint fixes

Took 3 minutes

src/Datasets.php

@@ -104,7 +104,7 @@ final class Datasets
                 $values                = array_merge($values, $dataset_data['values']);
             }
 
-            $dataSetDescriptions[] = $description." with ".implode(" / ", $partialDescriptions);
+            $dataSetDescriptions[] = $description . ' with ' . implode(' / ', $partialDescriptions);
             $dataSetValues[]       = $values;
         }
 
@@ -139,6 +139,7 @@ final class Datasets
             }
             $result = $tmp;
         }
+
         return $result;
     }