bpo-38771: Explict test for None in code example (GH-17108)

diff --git a/Doc/library/collections.rst b/Doc/library/collections.rst
index 90a3f4bea9a45b29b3acfda691bed8109c907e0f..a5e8d04099b22f9acc0dc58d78466791dd9d6e37 100644 (file)
--- a/Doc/library/collections.rst
+++ b/Doc/library/collections.rst
@@ -162,7 +162,7 @@ environment variables which in turn take precedence over default values::
         parser.add_argument('-u', '--user')
         parser.add_argument('-c', '--color')
         namespace = parser.parse_args()
-        command_line_args = {k:v for k, v in vars(namespace).items() if v}
+        command_line_args = {k: v for k, v in vars(namespace).items() if v is not None}
 
         combined = ChainMap(command_line_args, os.environ, defaults)
         print(combined['color'])