Enumeration of all the j-element sublists of a list of
given number of elements.
The procedure first has to be called with L containing first
j 1's then padding 0's. Afterwards it has to be called with the
previous configuration it gave.
- L a list of flags (0,1), providing a
characteristic list for the list whose sublists has to be generated.
- a list of flags, the next configuration in the
enumeration. If there is no more sublists to be generated, it
returns the empty list.