Here's a working example with the python code you cited:

Usage: tree.py -f [file limit] <directory>

If a number is specified for -f [file limit] then ... <additional files> is printed and the other files are skipped. Additional directories should not be skipped however. If the file limit is set to 10000 (default) this acts as no limit

#! /usr/bin/env python
# tree.py
#
# Written by Doug Dahms
# modified by glallen @ StackExchange
#
# Prints the tree structure for the path specified on the command line

from os import listdir, sep
from os.path import abspath, basename, isdir
from sys import argv

def tree(dir, padding, print_files=False, limit=10000):
    print padding[:-1] + '+-' + basename(abspath(dir)) + '/'
    padding = padding + ' '
    limit = int(limit)
    files = []
    if print_files:
        files = listdir(dir)
    else:
        files = [x for x in listdir(dir) if isdir(dir + sep + x)]
    count = 0
    for file in files:
        count += 1
        path = dir + sep + file
        if isdir(path):
            print padding + '|'
            if count == len(files):
                tree(path, padding + ' ', print_files, limit)
            else:
                tree(path, padding + '|', print_files, limit)
        else:
            if limit == 10000:
                print padding + '|'
                print padding + '+-' + file
                continue
            elif limit == 0:
                print padding + '|'
                print padding + '+-' + '... <additional files>'
                limit -= 1
            elif limit <= 0:
                continue
            else:
                print padding + '|'
                print padding + '+-' + file
                limit -= 1

def usage():
    return '''Usage: %s [-f] [file-listing-limit(int)] <PATH>
Print tree structure of path specified.
Options:
-f          Print files as well as directories
-f [limit]  Print files as well as directories up to number limit
PATH        Path to process''' % basename(argv[0])

def main():
    if len(argv) == 1:
        print usage()
    elif len(argv) == 2:
        # print just directories
        path = argv[1]
        if isdir(path):
            tree(path, ' ')
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    elif len(argv) == 3 and argv[1] == '-f':
        # print directories and files
        path = argv[2]
        if isdir(path):
            tree(path, ' ', True)
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    elif len(argv) == 4 and argv[1] == '-f':
        # print directories and files up to max
        path = argv[3]
        if isdir(path):
            tree(path, ' ', True, argv[2])
        else:
            print 'ERROR: \'' + path + '\' is not a directory'
    else:
        print usage()

if __name__ == '__main__':
    main()

When run, it should produce output similar to:

user@host /usr/share/doc $ python /tmp/recipe-217212-1.py -f 2 . | head -n 40
+-doc/
  |
  +-libgnuradio-fft3.7.2.1/
  | |
  | +-copyright
  | |
  | +-changelog.Debian.gz
  |
  +-libqt4-script/
  | |
  | +-LGPL_EXCEPTION.txt
  | |
  | +-copyright
  | |
  | +-... <additional files>
  |
  +-xscreensaver-gl/
  | |
  | +-copyright
  | |
  | +-changelog.Debian.gz
  | |
  | +-... <additional files>

Use options -r and -e:

btrfs qgroup show -pcre /path

If you're forced to use ext3, then using LVM is probably your best solution. Create a new filesystem per project. That would look something like this:

# Create a 10g filesystem for "project1" in volume group "vg0"
lvcreate -L 10g -n project1 vg0

# Create an ext3 filesystem.
mke2fs -j /dev/vg0/project1

# Mount it (obviously you would want this in /etc/fstab)
mount /dev/vg0/project1 /projects/project1

Growing the project filesystems is easy:

# Add 2GB to the volume.
lvextend -L +2g /dev/vg0/project1

# Grow the filesystem.
resize2fs /dev/vg0/project1

There is no specific limit on the number of files or subdirectories within a given directory. There are limits on the total number of inodes in a file system depending on how the file system was built and (mostly) how much space there is in total in the file system. Each named object requires an inode (but, thanks to hard links, a single inode can have multiple names). Thus, the limit is primarily controlled by the space available in the file system.

There are usually limits on how deep a directory hierarchy can be — that's the POSIX constant {PATH_MAX} defined (or not) in <limits.h>, and the related lower-bounds on the minimum acceptable value for {PATH_MAX} — {_XOPEN_PATH_MAX} (1024) and {_POSIX_PATH_MAX} (256).

You can use the functions fpathconf() and pathconf() to find properties of file systems at run-time. The related function sysconf() handles other configuration properties.