Add comments to explain the lambda:

Carreau · Carreau · commit f4206657bafa · 2020-06-05T11:16:45.000-07:00
See ipython#12355
diff --git a/IPython/terminal/pt_inputhooks/qt.py b/IPython/terminal/pt_inputhooks/qt.py
@@ -45,6 +45,8 @@ def inputhook(context):
                                           QtCore.QSocketNotifier.Read)
         try:
             # connect the callback we care about before we turn it on
+            # lambda is necessary as PyQT inspect the function signature to know
+            # what arguments to pass to. See https://github.com/ipython/ipython/pull/12355
             notifier.activated.connect(lambda: event_loop.exit())
             notifier.setEnabled(True)
             # only start the event loop we are not already flipped
