code: def test_generate_stc_single_hemi(_get_fwd_labels):
      """Test generation of source estimate, single hemi."""
      fwd, labels = _get_fwd_labels
      labels_single_hemi = labels[
          1:
      ]  # keep only labels in one hemisphere
  
      mylabels = []
      for i, label in enumerate(labels_single_hemi):
          new_label = Label(
              vertices=label.vertices,
              pos=label.pos,
              values=2 * i * np.ones(len(label.values)),
              hemi=label.hemi,
              comment=label.comment,
          )
          mylabels.append(new_label)
  
      n_times = 10
      tmin = 0
      tstep = 1e-3
  
      stc_data = np.ones((len(labels_single_hemi), n_times))
      stc = simulate_stc(fwd["src"], mylabels, stc_data, tmin, tstep)
  
      for label in labels_single_hemi:
          idx = _get_idx_label_stc(label, stc)
          assert np.all(stc.data[idx] == 1.0)
          assert stc.data[idx].shape[1] == n_times
  
      # test with function
      def fun(x):
          return x**2
  
      stc = simulate_stc(
          fwd["src"], mylabels, stc_data, tmin, tstep, fun
      )
  
      # the first label has value 0, the second value 2, the third value 6
  
      for i, label in enumerate(labels_single_hemi):
          if label.hemi == "lh":
              hemi_idx = 0
          else:
              hemi_idx = 1
  
          idx = np.intersect1d(stc.vertices[hemi_idx], label.vertices)
          idx = np.searchsorted(stc.vertices[hemi_idx], idx)
  
          if hemi_idx == 1:
              idx += len(stc.vertices[0])
  
          res = ((2.0 * i) ** 2.0) * np.ones((len(idx), n_times))
          assert_array_almost_equal(stc.data[idx], res)
  
file_path: mne-python/mne/simulation/tests/test_source.py
imports: import numpy
  import pytest
  from numpy.testing import assert_array_almost_equal, assert_array_equal, assert_equal
  from mne import convert_forward_solution, pick_types_forward, read_forward_solution, read_label
  from mne.datasets import testing
  from mne.label import Label
  from mne.simulation import SourceSimulator, simulate_sparse_stc, simulate_stc
label_desc: Use image node_id 5 for calling a global function with example usage: test_generate_stc_single_hemi(_get_fwd_labels) and returns: unknown