Complete docstring

Signed-off-by: Philippe Ombredanne <[email protected]>

Author: pombredanne

src/commoncode/hash.py

@@ -278,7 +278,8 @@ def multi_checksums(location, checksum_names=("md5", "sha1", "sha256", "sha512",
     content of the file at ``location``. Use the ``checksum_names`` list of checksum names. The
     mapping is guaranted to contains all the requested names as keys. If the location is not a file,
     or if the file is empty, the values are None.
-    The purpose of this function is
+    The purpose of this function is to avoid read the same file multiple times
+    to compute different checksums. 
     """
     if not filetype.is_file(location):
         return {name: None for name in checksum_names}