Watching a directory tree on Unix

This script continuously monitors the paths and their subdirectories for changes. If any files or directories are modified, the callable 'func' is called with a list of the modified paths of both files and directories.

'func' can return a Boolean value for rescanning; if it returns True, the directory tree will be rescanned without calling func() for any found changes. (This is so func() can write changes into the tree and prevent itself from being immediately called again.) & prevent t;