flesh out open() docstring
diff --git a/Lib/shelve.py b/Lib/shelve.py
index 9477c5d..982c4e2 100644
--- a/Lib/shelve.py
+++ b/Lib/shelve.py
@@ -157,7 +157,13 @@
def open(filename, flag='c', binary=False):
"""Open a persistent dictionary for reading and writing.
- Argument is the filename for the dbm database.
+ The filename parameter is the base filename for the underlying database.
+ As a side-effect, an extension may be added to the filename and more
+ than one file may be created. The optional flag parameter has the
+ same interpretation as the flag parameter of anydbm.open(). The
+ optional binary parameter may be set to True to force the use of binary
+ pickles for serializing data values.
+
See the module's __doc__ string for an overview of the interface.
"""