docstr: Compute the test-statistic (CVM) between the reference window(s) and test window.
  If a given test-window is not yet full then a test-statistic of np.nan is returned for that window.
  
  Parameters
  ----------
  x_t
      A single instance.
  
  Returns
  -------
  Estimated CVM test statistics between reference window and test window(s).
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code: def score(self, x_t: Union[np.ndarray, Any]) -> np.ndarray:
      """
      Compute the test-statistic (CVM) between the reference window(s) and test window.
      If a given test-window is not yet full then a test-statistic of np.nan is returned for that window.
  
      Parameters
      ----------
      x_t
          A single instance.
  
      Returns
      -------
      Estimated CVM test statistics between reference window and test window(s).
      """
      x_t = super()._preprocess_xt(x_t)
      self._update_state(x_t)
  
      stats = np.zeros(
          (len(self.window_sizes), self.n_features), dtype=np.float32
      )
      for k, ws in enumerate(self.window_sizes):
          if self.t >= ws:
              ref_cdf_win = (
                  np.sum(self.ids_ref_wins[:, -ws:], axis=0) / self.n
              )
              win_cdf_ref = np.sum(self.ids_wins_ref[-ws:], axis=0) / ws
              win_cdf_win = (
                  np.sum(self.ids_wins_wins[-ws:, -ws:], axis=0) / ws
              )
              ref_cdf_diffs = self.ref_cdf_ref - win_cdf_ref
              win_cdf_diffs = ref_cdf_win - win_cdf_win
              sum_diffs_2 = np.sum(
                  ref_cdf_diffs * ref_cdf_diffs, axis=0
              ) + np.sum(win_cdf_diffs * win_cdf_diffs, axis=0)
              stats[k, :] = _normalise_stats(sum_diffs_2, self.n, ws)
          else:
              stats[k, :] = np.nan
      return stats
  
imports: import numpy
  from typing import Any, Callable, List, Optional, Union
  from alibi_detect.base import DriftConfigMixin
  from alibi_detect.cd.base_online import BaseUniDriftOnline
  from alibi_detect.utils.misc import quantile
  import numba
  from tqdm import tqdm
  import warnings
label_desc: Use image node_id 7 for calling the CVMDriftOnline obj's underlying member method code with example usage: obj.score(x_t) and returns: stats