If there are \(n\) files, there must be either \(1\) or \(n\)
directories. If there is one directory, then all \(n\) files are moved
there. If there are \(n\) directories, then each file is put into its
respective directory. This function also works to move directories.
If you try to move files to a directory that doesn't exist, the directory is
first created and then the files are put inside.