How to call functions inside a function in Python?

Help with this C function?

• Can someone help me write this function for a project? In this project you will write functions that simulate some of the functionality of the UNIX filesystem and common commands. Your program will allow simulated files and directories to be created, and permit navigating around the directory structure by changing the current location in the filesystem. The purpose of the project is to use linked structures and memory management in C. Note that you must use linked data structures in implementing the project. This function , mkfs, should initialize its Filesystem parameter, but exactly what that will do depends upon the way you decide to represent and store the components of a filesystem. This function must be called to initialize any Filesystem variable, before any other operations are performed on that variable. Every call to mkfs() must initialize the parameter Filesystem in such a way that each returned value represents a different filesystem, so calling mkfs several times will not cause separate Filesystem variables to share any files or directories. The result of calling any of the other functions on a Filesystem variable before mkfs() is called on it is undefined. The result of calling any of the other functions is also undefined if mkfs() was first called, but its argument was just NULL. After calling this function with a non–NULL parameter any of the other functions can be called. The user of your functions (which includes any of our tests) must call mkfs() on any Filesystem variables that are declared or created before calling any of the other functions on them, if they want them to be properly initialized, and they must call all of the other functions only after calling mkfs() on a non–NULL Filesystem variable. After calling this function the parameter Filesystem (assuming it was non–NULL) should contain only a root directory.

• Answer:

  Just to get one thing straight, is this actually messing with the directories and file systems, or more or less a virtual filesystem that doesn't actually change anything, just implies that it could?