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README.md

@@ -228,4 +228,13 @@ with escape(error_callback=lambda: print('Attention!')):
     pass
 ```
 
+If you pass a callback as a `before` parameter, it'll be called before the code block anyway:
+
+```python
+with escape(before=lambda: print('Attention!')):
+    pass
+```
+
+Notice, if an error occurs in this callback that will not be suppressed, the main code will not be executed - an exception will be raised before it starts executing.
+
 If an error occurs in one of the callbacks, the exception will be suppressed if it would have been suppressed if it had happened in a wrapped code block or function. You can see the corresponding log entry about this if you [pass the logger object](#logging) for registration. If the error inside the callback has been suppressed, it will not affect the logic that was wrapped by `escape` in any way.