How To Add A Sublist To A Sublist?

I want to append a sublist to the previous sublist under certain circumstances, i.e. if its length is less than 2. So, the length of [5] less than 2 and now the previous list is to be extended with the 5 (a+b).

a = [1,1,1,1]
b = [5]
c = [1,1,1]
d = [1,1,1,1,1]
e = [1,2]
f = [1,1,1,1,1,1]

L = [a,b,c,d,e,f]

print 'List:', L

def short(lists):
    result = []
    for value in lists:
        if len(value) <= 2 and result:
            result[-1] = result[-1] + value
    return result

result = short(L)
print 'Result:', result

The result should be: [[1, 1, 1, 1, 5], [1, 1, 1], [1, 1, 1, 1, 1, 2], [1, 1, 1, 1, 1, 1]]

But from my code, I get: []

This might help

Ex:

a = [1,1,1,1]
b = [5]
c = [1,1,1]
d = [1,1,1,1,1]
e = [1,2]
f = [1,1,1,1,1,1]

L = [a,b,c,d,e,f]

print( 'List:', L)

def short(lists):
    result = []
    for value in lists:
        if len(value) <= 2:            #check len
            result[-1].extend(value)   #extend to previous list
        else:
            result.append(value)       #append list. 
    return result

result = short(L)
print( 'Result:', result)

Output:

List: [[1, 1, 1, 1], [5], [1, 1, 1], [1, 1, 1, 1, 1], [1, 2], [1, 1, 1, 1, 1, 1]]
Result: [[1, 1, 1, 1, 5], [1, 1, 1], [1, 1, 1, 1, 1, 1, 2], [1, 1, 1, 1, 1, 1]]