diff --git a/voussoirkit/sqlhelpers.py b/voussoirkit/sqlhelpers.py
index 533c3b2..327d498 100644
--- a/voussoirkit/sqlhelpers.py
+++ b/voussoirkit/sqlhelpers.py
@@ -114,6 +114,9 @@ def update_filler(pairs, where_key):
     return (qmarks, bindings)
 
 def hex_byte(byte):
+    '''
+    Return the hex string for this byte. 00-ff.
+    '''
     if byte not in range(0, 256):
         raise ValueError(byte)
     return hex(byte)[2:].rjust(2, '0')