working with combinations object in python
Question: 
    >>> import itertools
    >>> n = [1,2,3,4]
    >>> combObj = itertools.combinations(n,3)
    >>>
    >>> combObj
    <itertools.combinations object at 0x00000000028C91D8>
    >>>
    >>> list(combObj)
    [(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]
    >>>
    >>> for i in list(combObj): #This prints nothing
    ...     print(i)
    ...
    

  1. How can i iterate through combObj ?

  2. How can i convert  
`[(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]`  
to  
`[[1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]]`


Answer: Once you iterate through the `itertools.combinations` object once, it's been
used up and you can't iterate over it a second time.

If you need to reuse it, the proper way is to make it a `list` or `tuple` as
you did. All you need to do is give it a name (assign it to a variable) so it
sticks around.

    
    
    combList = list(combObject) # Don't iterate over it before you do this!
    

If you want to iterate over it just once, you just don't call `list` on it at
all:

    
    
    for i in combObj: # Don't call `list` on it before you do this!
        print(i)
    

Side note: The standard way to name object instances / normal variables would
be `comb_obj` rather than `combObj`. See
[PEP-8](http://www.python.org/dev/peps/pep-0008/) for more info.

To convert the inner `tuple`s to `list`s, use a list comprehension and the
`list()` built-in:

    
    
    comb_list = [(1, 2, 3), (1, 2, 4), (1, 3, 4), (2, 3, 4)]
    comb_list = [list(item) for item in comb_list]
    

