code: def _check_if_num_levels_is_even(num_levels: int):
      """
      Checks if the number of levels is even. If not, raises a warn.
  
      Parameters
      ----------
      num_levels: int
          Number of levels
      """
      if not num_levels % 2 == 0:
          warnings.warn(
              "num_levels should be an even number, "
              "sample may be biased"
          )
  
imports: import numpy
  from typing import Dict
  import numpy.random
  import warnings
  from .local import LocalOptimisation
  from .brute import BruteForce
  from .strategy import SampleMorris
  from SALib.sample import common_args
  from SALib.util import scale_samples, read_param_file, compute_groups_matrix, _define_problem_with_groups, _compute_delta, _check_groups
label_desc: Use image node_id 8 for calling a global function with example usage: _check_if_num_levels_is_even(num_levels) without return types