------------------------------------------------------------------------------------
# what does os.walk yield when links are present?

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l test1
drwxr-xr-x  3 blue  wheel  102 Jan 28 17:40 dir
lrwxr-xr-x  1 blue  wheel    3 Feb  9 06:43 dirlink -> dir
-rw-r--r--  1 blue  wheel    5 Jan 28 17:32 file
lrwxr-xr-x  1 blue  wheel    4 Feb  9 06:43 filelink -> file
lrwxr-xr-x  1 blue  wheel   14 Feb  9 06:43 nestedfilelink -> dir/nestedfile

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ py3
>>> import os


# NOFOLLOW
>>> for (dir, subs, files) in os.walk('test1', followlinks=False):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
... 
'test1' ['dir', 'dirlink'] ['file', 'filelink', 'nestedfilelink']
'test1' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/test1'

'test1/dir' [] ['nestedfile']
'test1/dir' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/test1/dir'


# FOLLOW
>>> for (dir, subs, files) in os.walk('test1', followlinks=True):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
... 
'test1' ['dir', 'dirlink'] ['file', 'filelink', 'nestedfilelink']
'test1' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/test1'

'test1/dir' [] ['nestedfile']
'test1/dir' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/test1/dir'

'test1/dirlink' [] ['nestedfile']
'test1/dirlink' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/test1/dir'


-----------------------------------------------------------------------------------
# when recursive links are present?


# RECURSIVE

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp
drwxr-xr-x  3 blue  wheel  102 Feb  9 11:38 sub

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp/sub
drwxr-xr-x  3 blue  wheel  102 Feb  9 11:40 subsub

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp/sub/subsub
lrwxr-xr-x  1 blue  wheel  9 Feb  9 11:40 recur -> ../../sub


# NOFOLLOW
>>> for (dir, subs, files) in os.walk('temp', followlinks=False):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
... 
'temp' ['sub'] []
'temp' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp'

'temp/sub' ['subsub'] []
'temp/sub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub' ['recur'] []
'temp/sub/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'


# FOLLOW
>>> level = 0
>>> for (dir, subs, files) in os.walk('temp', followlinks=True):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
...     if level > 10: break
...     level += 1
... 
'temp' ['sub'] []
'temp' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp'

'temp/sub' ['subsub'] []
'temp/sub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub' ['recur'] []
'temp/sub/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'

'temp/sub/subsub/recur' ['subsub'] []
'temp/sub/subsub/recur' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub/recur/subsub' ['recur'] []
'temp/sub/subsub/recur/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'

'temp/sub/subsub/recur/subsub/recur' ['subsub'] []
'temp/sub/subsub/recur/subsub/recur' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub/recur/subsub/recur/subsub' ['recur'] []
'temp/sub/subsub/recur/subsub/recur/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'

'temp/sub/subsub/recur/subsub/recur/subsub/recur' ['subsub'] []
'temp/sub/subsub/recur/subsub/recur/subsub/recur' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub' ['recur'] []
'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'

'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur' ['subsub'] []
'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'

'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur/subsub' ['recur'] []
'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur/subsub' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub/subsub'

'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur/subsub/recur' ['subsub'] []
'temp/sub/subsub/recur/subsub/recur/subsub/recur/subsub/recur/subsub/recur' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp/sub'



# NONRECURSIVE BUT REPEATED

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp2
total 0
drwxr-xr-x  3 blue  wheel  102 Feb  9 12:09 dir1
drwxr-xr-x  3 blue  wheel  102 Feb  9 11:54 dir2
drwxr-xr-x  3 blue  wheel  102 Feb  9 11:54 dir3

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp2/dir1
-rw-r--r--  1 blue  wheel  5 Feb  9 12:09 file

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp2/dir2
lrwxr-xr-x  1 blue  wheel  7 Feb  9 11:54 dir1_A -> ../dir1

/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks$ ls -l temp2/dir3
lrwxr-xr-x  1 blue  wheel  7 Feb  9 11:54 dir1_B -> ../dir1


# NOFOLLOW
>>> for (dir, subs, files) in os.walk('temp2', followlinks=False):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
... 
'temp2' ['dir1', 'dir2', 'dir3'] []
'temp2' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2'

'temp2/dir1' [] ['file']
'temp2/dir1' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir1'

'temp2/dir2' ['dir1_A'] []
'temp2/dir2' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir2'

'temp2/dir3' ['dir1_B'] []
'temp2/dir3' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir3'


# FOLLOW
>>> for (dir, subs, files) in os.walk('temp2', followlinks=True):
...     print(*(repr(x) for x in (dir, subs, files)))
...     print('%r => %r\n' % (dir, os.path.realpath(dir)))
... 
'temp2' ['dir1', 'dir2', 'dir3'] []
'temp2' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2'

'temp2/dir1' [] ['file']
'temp2/dir1' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir1'

'temp2/dir2' ['dir1_A'] []
'temp2/dir2' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir2'

'temp2/dir2/dir1_A' [] ['file']
'temp2/dir2/dir1_A' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir1'

'temp2/dir3' ['dir1_B'] []
'temp2/dir3' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir3'

'temp2/dir3/dir1_B' [] ['file']
'temp2/dir3/dir1_B' => '/MY-STUFF/Code/mergeall/test/ziptools/test-symlinks/temp2/dir1'