import os

# This is a function object: 1st param is the data item, 
# 2nd argument is name of current directory, 3rd arg is a list 
# of file names in that directory (obtained using os.listdir):
def lister(dummy, dirname, filesindir):
    print '[' + dirname + ']'
    for fname in filesindir:
      print os.path.join(dirname, fname)  #handle one file

if __name__ == "__main__":
   # 1st arg to walk is root directory from which ti
   # search, 2nd arg is function object, 3rd is opt data item
   # used as arg to function object:
   os.path.walk('.', lister, None)