code: def combinations_of_len(l, k):
      return list(
          chain.from_iterable(
              combinations(l, r) for r in range(1, k + 1)
          )
      )
  
imports: import pickle
  from itertools import chain, combinations
label_desc: Use image node_id 4 for calling a global function with example usage: combinations_of_len(l, k) and returns: list