def process_what_to_run_concepts(pairs_to_test):
    """Process concepts and pairs to test.

    Args:
      pairs_to_test: a list of concepts to be tested and a target (e.g,
       [ ("target1",  ["concept1", "concept2", "concept3"]),...])

    Returns:
      return pairs to test:
         target1, concept1
         target1, concept2
         ...
         target2, concept1
         target2, concept2
         ...

    """
    pairs_for_testing = []
    # prepare pairs for concept vs random.
    for pair in pairs_to_test:
        for concept in pair[1]:
            pairs_for_testing.append([pair[0], [concept]])
    return pairs_for_testing