*Note: I changed *2 < *i
*<=
*k into *2 <= *i *<=
*k,
in the text below. The previous version was underspecified, since it allowed
N _{2} to be arbitrary, instead of being equal to N_{0
}+
N_{1}.*

This program should take you about an hour. Please get it over with as soon as possible.

Write the procedure `fib_subsets(S)` which returns the set of
all subsets of set `S` that represent a "fibonacci set".

For our purposes, we'll call a fibonacci set a set of (positive or negative) integers

{such thatN}_{0}, ... , N_{k}, k >1

An example of a fibonacci set is{29, 4, 3, 11,18, 7}.