code: def get_complex_coefficients(self, params):
          
          return np.empty(0), np.empty(0), np.empty(0), np.empty(0)
docs: Get the arrays ``alpha_complex_*`` and ``beta_complex_*``
  
          This method should be overloaded by subclasses to return the arrays
          ``alpha_complex_real``, ``alpha_complex_imag``, ``beta_complex_real``,
          and ``beta_complex_imag`` given the current parameter settings. By
          default, this term is empty.
  
          Returns:
              (array[j_complex], array[j_complex], array[j_complex],
              array[j_complex]): ``alpha_complex_real``, ``alpha_complex_imag``,
              ``beta_complex_real``, and ``beta_complex_imag`` as described
              above. ``alpha_complex_imag`` can be omitted and it will be
              assumed to be zero.