code: def test_output_multivariate_time_series_corr():
      """
      Test the output of the correlation matrix
      """
  
      time_series = pd.Series(range(10), name="series_1")
      other = pd.DataFrame(
          {
              "series_2": range(10),
              "series_3": [9, 2, 3, 8, 2, 6, 0, 8, 6, 1],
          }
      )
  
      expected = pd.DataFrame(
          data={
              "series_2": [1.0, 1.0, 1.0, 1.0, 1.0],
              "series_3": [
                  -0.21854656,
                  -0.02836,
                  -0.11964501,
                  -0.45360921,
                  -0.17251639,
              ],
          },
          index=pd.RangeIndex(start=0, stop=5, step=1),
      )
      expected.index.name = "lag"
  
      results = multivariate_time_series_corr(
          time_series=time_series, other=other, lags=5
      )
  
      pd.testing.assert_frame_equal(results, expected)
  
imports: import re
  import pytest
  import pandas
  from skforecast.utils.utils import multivariate_time_series_corr
label_desc: Use image node_id 1 for calling a global function with example usage: test_output_multivariate_time_series_corr() without return types