docs: def value_count(x, value):
      """
      Count occurrences of `value` in time series x.
  
      :param x: the time series to calculate the feature of
      :type x: numpy.ndarray
      :param value: the value to be counted
      :type value: int or float
      :return: the count
      :rtype: int
      """
      if not isinstance(x, (np.ndarray, pd.Series)):
          x = np.asarray(x)
  
      if np.isnan(value):
          return np.isnan(x).sum()
      else:
          return x[x == value].size