# Run Length Encoding Implement run-length encoding and decoding. Run-length encoding (RLE) is a simple form of data compression, where runs (consecutive data elements) are replaced by just one data value and count. For example we can represent the original 53 characters with only 13. ```text "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWB" -> "12WB12W3B24WB" ``` RLE allows the original data to be perfectly reconstructed from the compressed data, which makes it a lossless data compression. ```text "AABCCCDEEEE" -> "2AB3CD4E" -> "AABCCCDEEEE" ``` 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/` directory. For example, if you're submitting `bob.py` for the Bob exercise, the submit command would be something like `exercism submit /python/bob/bob.py`. For more detailed information about running tests, code style and linting, please see the [help page](http://exercism.io/languages/python). ## Source Wikipedia [https://en.wikipedia.org/wiki/Run-length_encoding](https://en.wikipedia.org/wiki/Run-length_encoding) ## Submitting Incomplete Solutions It's possible to submit an incomplete solution so you can see how others have completed the exercise.