docs: def cat_trials(x3d):
      """Concatenate trials along time axis.
  
      Parameters
      ----------
      x3d : array, shape (t, m, n)
          Segmented input data with t trials, m signals, and n samples.
  
      Returns
      -------
      x2d : array, shape (m, t * n)
          Trials are concatenated along the second axis.
  
      See also
      --------
      cut_segments : Cut segments from continuous data.
  
      Examples
      --------
      >>> x = np.random.randn(6, 4, 150)
      >>> y = cat_trials(x)
      >>> y.shape
      (4, 900)
      """
      x3d = atleast_3d(x3d)
      t = x3d.shape[0]
      return np.concatenate(np.split(x3d, t, 0), axis=2).squeeze(0)