Spanner: Snapshot begin in docs (googleapis#4630)

chemelnucfin · web-flow · commit 9a18400724f5 · 2017-12-19T14:50:22.000-08:00
diff --git a/docs/spanner/snapshot-usage.rst b/docs/spanner/snapshot-usage.rst
@@ -50,6 +50,10 @@ reused.
 
     snapshot = database.snapshot(multi_use=True)
 
+:meth:`~.spanner_v1.snapshot.Snapshot.begin` can only be used on a
+snapshot with ``multi_use=True``.  In which case it is also necessary
+to call if you need to have multiple pending operations.
+
 Read Table Data
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