Please explain the working of this code? [closed]

Break it down into pieces

def gSubsets(L): #recursive function
    if len(L) == 0: #when weve reached the last subset we then have to handle an empty list
        print '2'
        return [[]] #returns a list of lists for the small in smaller
    smaller = gSubsets(L[:-1]) #get subsets by recursive call for all elements in the list except the last one
    extra = L[-1:] #get the last element in the list not used in this recursive call
    print L     
    new = []
    for small in smaller: #loop through list of lists from recursive call
        new.append(small+extra) #append all combinations of the last element in the list to every other element in the same list to new
    return smaller+new #return subset with new combinations

print gSubsets([1,2])

this outputs

>>> 2
>>> [1]
>>> [1, 2]
>>> [[], [1], [2], [1, 2]]

by the way, in python you should use underscores in your variable and function names (its the preferred syntax) and I would work on your variable names too.. you want them to be very specific so anyone else coming by can understand what it is right away.. this is how I would rename the variables.

def generate_subsets_from_list(input_list):
    if len(input_list) == 0:
        # print '2'  -- not sure why you are printing 2 here?
        return [[]]
    subsets = generate_subsets_from_list(input_list[:-1]) 
    last_element = L[-1:]
    print L     
    return_list = []
    for subset in subsets:
        return_list.append(subset+last_element)
    return subsets+return_list

initial_list = [1,2]
print generate_subsets_from_list(initial_list)

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