Addition of Example 4 notebook - modelling of the Iowa Gambling Task

[sashapustota]

Work in progress

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.64%. Comparing base (19bba47) to head (59487e2).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #192 +/- ## ======================================= Coverage 95.64% 95.64% ======================================= Files 23 23 Lines 1194 1194 ======================================= Hits 1142 1142 Misses 52 52 ```

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