Sum of list items

[tristanfermat]

I have this one but It doesn't work as I wanted.

import itertools
import functools

test_matrix = []
stuff = [100,500,300,200]
for L in range(0, len(stuff)+1):
    
   for subset in itertools.combinations(stuff, L):
         test_matrix.append(subset)
       
while True:       
    res = functools.reduce(lambda i, j: i if 4000 < sum(j)
                          else j, test_matrix)
    
    
    test_matrix.remove(res)
    a = sum(int(b) for b in res)

    print (a)
    print ("Maximum sum sublist is : " + str(res))