README.md in trackler-2.2.1.75

- old
+ new

@@ -21,9 +21,24 @@
 For simplicity, you can assume that the unencoded string will only contain
 the letters A through Z (either lower or upper case) and whitespace. This way
 data to be encoded will never contain any numbers and numbers inside data to
 be decoded always represent the count for the following character.
 
+## Exception messages
+
+Sometimes it is necessary to raise an exception. When you do this, you should include a meaningful error message to
+indicate what the source of the error is. This makes your code more readable and helps significantly with debugging. Not
+every exercise will require you to raise an exception, but for those that do, the tests will only pass if you include
+a message.
+
+To raise a message with an exception, just write it as an argument to the exception type. For example, instead of
+`raise Exception`, you shold write:
+
+```python
+raise Exception("Meaningful message indicating the source of the error")
+```
+
+
 ## Submitting Exercises
 
 Note that, when trying to submit an exercise, make sure the solution is in the `exercism/python/<exerciseName>` directory.
 
 For example, if you're submitting `bob.py` for the Bob exercise, the submit command would be something like `exercism submit <path_to_exercism_dir>/python/bob/bob.py`.