From 65d8e78c5f412f624cbc49db8aece156c4701798 2020-07-21 17:14:15
From: Matthias Bussonnier <bussonniermatthias@gmail.com>
Date: 2020-07-21 17:14:15
Subject: [PATCH] add WN

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diff --git a/docs/source/whatsnew/pr/transformer-call.rst b/docs/source/whatsnew/pr/transformer-call.rst
new file mode 100644
index 0000000..5e8d9ef
--- /dev/null
+++ b/docs/source/whatsnew/pr/transformer-call.rst
@@ -0,0 +1,5 @@
+Input transformers are now called only once in the execution path of `InteractiveShell`, allowing to register
+transformer that potentially have side effects (note that this is not recommended). `should_run_async`, and
+`run_cell_async` now take a recommended optional `transformed_cell`, and `preprocessing_exc_tuple` parameters that will
+become mandatory at some point in the future; that is to say cells need to be explicitly transformed to be valid Python
+syntax ahead of trying to run them. :ghpull:`12440`