docstr: Update online state based on the provided test instance.
  
  Parameters
  ----------
  x_t
      The test instance.
docstr_tok: ["Update","online","state","based","on","the","provided","test","instance",".","Parameters","--","--","--","--","--","x_t","The","test","instance","."]
code: def _update_state(self, x_t: np.ndarray):
      """
      Update online state based on the provided test instance.
  
      Parameters
      ----------
      x_t
          The test instance.
      """
      self.t += 1
      if self.t == 1:
          # Initialise stream
          self.xs = x_t
      else:
          # Update stream
          self.xs = np.concatenate([self.xs, x_t])
  
imports: from tqdm import tqdm
  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
  from scipy.stats import hypergeom
  import numba
  import warnings
label_desc: Use image node_id 6 for calling the FETDriftOnline obj's underlying member method code with example usage: obj._update_state(x_t) without return types