Python: build and initialize a dictionary from a list of lists

OK, so building on the last post. Here's a general purpose function that takes a list of desired key-lists, and returns a multi-dimensional data dictionary.

##
## Takes dictionary and a list of desired keys
## adds the keys to the dictionary, initializing them to input parameter
#
# @param input_dictionary Name of input dictionary
# @param input_keys List of desired keys
# @param input_default [optional] Value to initialize each dictionary entry
# if input_default parameter not given, then 0 is used
#
#
def setDictionaryDefaults(input_dictionary,input_keys,input_default=0):
    for key in input_keys:
      input_dictionary.setdefault(key,input_default)


##
# Given a list of lists, build a multidimensional dictionary, initialized to optional input parameter
#
# @param list_of_lists = list of key-lists
# @param input_default [optional] Value to initialize each dictionary entry
# if input_default parameter not given, then 0 is used
def buildDictionary(list_of_lists,input_default=0):
    d=dict()
    number_of_lists=len(list_of_lists)
    if number_of_lists==0:
        return d
    setDictionaryDefaults(d,list_of_lists[0],input_default)
    if number_of_lists==1:
        return d
    next_d=dict()
    for next_list in list_of_lists[1:]:
        setDictionaryDefaults(next_d,next_list,d)
        d=next_d
        next_d=dict()
    return d

Here I test it:

 Python 2.4.1 (#2, Jul 24 2007, 12:14:31)
[GCC 3.2.3 20030502 (Red Hat Linux 3.2.3-34)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from lists_to_dict import buildDictionary
>>> a=['a','b']
>>> c=[a]
>>> d=buildDictionary(c,1)
>>> d
{'a': 1, 'b': 1}
>>> q=['R','S','T']
>>> x=['X','XX','XXX']
>>> y=['Y','YY']
>>> c=[a,q,x,y]
>>> c
[['a', 'b'], ['R', 'S', 'T'], ['X', 'XX', 'XXX'], ['Y', 'YY']]
>>> d=buildDictionary(c,1)
>>> d
{'Y': {'X': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}, 'XX': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}, 'XXX': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}}, 'YY': {'X': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}, 'XX': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}, 'XXX': {'S': {'a': 1, 'b': 1}, 'R': {'a': 1, 'b': 1}, 'T': {'a': 1, 'b': 1}}}}
>>>
>>> c=[]
>>> d=buildDictionary(c,1)
>>> d
{}
>>> a=['q','r']
>>> c=[a]
>>> buildDictionary(c)
{'q': 0, 'r': 0}
>>> d=buildDictionary(c)
>>> d
{'q': 0, 'r': 0}
>>>