code: def _reassign(check, clusters, base, num):
      """Reassign cluster numbers."""
      # reconfigure check matrix
      check[check == num] = base
      # concatenate new values into clusters array
      clusters[base - 1] = np.concatenate(
          (clusters[base - 1], clusters[num - 1])
      )
      clusters[num - 1] = np.array([], dtype=int)
  
imports: import numpy
  from scipy import ndimage, sparse
  from scipy.sparse.csgraph import connected_components
  from scipy.stats import f
  from scipy.stats import t
  from ..fixes import has_numba, jit
  from ..parallel import parallel_func
  from ..source_estimate import MixedSourceEstimate, SourceEstimate, VolSourceEstimate
  from ..source_space import SourceSpaces
  from ..utils import ProgressBar, _check_option, _pl, _validate_type, check_random_state, logger, split_list, verbose, warn
  from .parametric import f_oneway, ttest_1samp_no_p
label_desc: Use image node_id 8 for calling a global function with example usage: _reassign(check, clusters, base, num) without return types