diff --git a/cellveyor/constants.py b/cellveyor/constants.py
index 7d6bf28..95854f2 100644
--- a/cellveyor/constants.py
+++ b/cellveyor/constants.py
@@ -2,6 +2,7 @@
 
 from dataclasses import dataclass
 
+
 # humanreadable constant
 @dataclass(frozen=True)
 class Humanreadable:
@@ -10,8 +11,10 @@ class Humanreadable:
     Yes: str
     No: str
 
+
 humanreadable = Humanreadable(Yes="Yes", No="No")
 
+
 # markers constant
 @dataclass(frozen=True)
 class Markers: