code: def generate_mixes_using_all_examples(sourceid_to_exids, rs):
      """Generates mixes guaranteed to use every example at least once."""
      # Brute force way to ensure every example from every source is used at least
      # once. Just goes through every source, selects each example, and generates
      # a mix using random examples from other sources.
      # Number of final outputs is variable, depending on how many end up getting
      # deduped.
      sourceid_to_exids = copy.deepcopy(sourceid_to_exids)
      mixes = []
      for current_source in sourceid_to_exids:
          for current_exid in sourceid_to_exids[current_source]:
              mix = [current_exid]
              for other_source in sourceid_to_exids.keys() - set(
                  [current_source]
              ):
                  rs.shuffle(sourceid_to_exids[other_source])
                  mix.append(
                      next(
                          x
                          for x in sourceid_to_exids[other_source]
                          if x not in mix
                      )
                  )
              mixes.append(mix)
      return _dedup_mixes(mixes)
  
imports: import collections
  import copy
  import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: generate_mixes_using_all_examples(sourceid_to_exids, rs) and returns: _dedup_mixes