IMPORTANT:

The assignment should be done step by step:

1. Create a prototype of the system (this is just signatures of functions without implementation. It is not possible to create tests if you dont do this step. But this is not full implementation)
2. Create Tests (PyTest or Robot)
3. Provide implementation
4. Bugfixes

Task 1. Create in-memory File System (FS). The file system consists of 4 types of nodes: 1) Directory - can contain other directories and files. Directory can be empty or can have some elements. Number of elements in the directory should be