code: def ensure_all_wide_alt_ids_are_chosen(choice_col,
                                         alt_specific_vars,
                                         availability_vars,
                                         wide_data):
      
      sorted_alt_ids = np.sort(wide_data[choice_col].unique())
      try:
          problem_ids = [x for x in availability_vars
                         if x not in sorted_alt_ids]
          problem_type = "availability_vars"
          assert problem_ids == []
  
          problem_ids = []
          for new_column in alt_specific_vars:
              for alt_id in alt_specific_vars[new_column]:
                  if alt_id not in sorted_alt_ids and alt_id not in problem_ids:
                      problem_ids.append(alt_id)
          problem_type = "alt_specific_vars"
          assert problem_ids == []
      except AssertionError:
          msg = "The following alternative ids from {} are not "
          msg_2 = "observed in wide_data[choice_col]:\n{}"
          raise ValueError(msg.format(problem_type) + msg_2.format(problem_ids))
  
      return None
docs: Checks to make sure all user-specified alternative id's, both in
      `alt_specific_vars` and `availability_vars` are observed in the choice
      column of `wide_data`.