diff --git a/pypiper/const.py b/pypiper/const.py
index 2749529..0bfbdb6 100644
--- a/pypiper/const.py
+++ b/pypiper/const.py
@@ -1,6 +1,5 @@
 """ Pypiper constants. """
 
-
 CHECKPOINT_EXTENSION = ".checkpoint"
 DEFAULT_SAMPLE_NAME = "DEFAULT_SAMPLE_NAME"
 PIPELINE_CHECKPOINT_DELIMITER = "_"
diff --git a/pypiper/ngstk.py b/pypiper/ngstk.py
index 329b321..b607913 100755
--- a/pypiper/ngstk.py
+++ b/pypiper/ngstk.py
@@ -153,8 +153,7 @@ def get_file_size(self, filenames):
             return sum([self.get_file_size(filename) for filename in filenames])
 
         return round(
-            sum([float(os.stat(f).st_size) for f in filenames.split(" ")])
-            / (1024**2),
+            sum([float(os.stat(f).st_size) for f in filenames.split(" ")]) / (1024**2),
             4,
         )