diff --git a/segments.py b/segments.py
index 23f7331762bddb7a1759b37dbe5ac86e165b3ad8..a37fa39c169f54bd31cd3f86fc5e23b681dd2196 100755
--- a/segments.py
+++ b/segments.py
@@ -1,7 +1,10 @@
 #!/usr/bin/env python3
 
-# segmentation
-#   OUTPUT: a graph-tool "gt" file (change name as needed)
+"""Collapses the input graph into a new graph: the graph of
+segments. An edge of the graph is a segment. The new graph is output
+in the binary format of graph-tool.
+
+"""
 
 import graph_tool
 import time