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+Default logic of the `fit_transform()`:
+1. execute it on the last Step.
+1. Step is fitted and transformed. Any data or models will be overridden (default setup).
+1. If `force_fitting` is not obligatory, then look for cache:
+    1. if output is cached, then use it. In such situation `fit_tranform()` was just taking output from cache.
+    1. If output is not cached -> steppy looks for persisted (saved to disk) output. If exist, `fit_tranform()` was just loading output from the project directory.