diff --git a/DAS/block.py b/DAS/block.py
index 228e743..10ff30d 100644
--- a/DAS/block.py
+++ b/DAS/block.py
@@ -21,10 +21,12 @@ class Block:
         self.data |= merged.data
 
     def getSegment(self, rowID, columnID):
+        """Check whether a segment is included"""
         return self.data[rowID*self.blockSize + columnID]
 
-    def setSegment(self, rowID, columnID, v = 1):
-        self.data[rowID*self.blockSize + columnID] = v
+    def setSegment(self, rowID, columnID, value = 1):
+        """Set value for a segment (default 1)"""
+        self.data[rowID*self.blockSize + columnID] = value
 
     def getColumn(self, columnID):
         """It returns the block column corresponding to columnID."""