docs: def rescale_array_from_z1z2(array_rs, coef_rs=None):
      """Restore the values in a numpy array rescaled to the [z1,z2] interval.
  
      The transformation is carried out following the relation
      array = (array_rs + c_flux)/b_flux
      as explained in Appendix B1 of Cardiel (2009, MNRAS, 396, 680)
  
      Parameters
      ----------
      array_rs : numpy array
          Numpy array previously rescaled to the [z1,z2] interval with
          the function rescale_array_to_z1z2().
      coef_rs : tuple, floats
          Coefficients b_flux and c_flux previously employed in the
          rescaling operation. This tuple is one of the parameters
          returned by function_rescale_array_to_z1z2().
  
      Returns
      -------
      array : numpy array
          Array with restored values.
  
      """
  
      if type(array_rs) is not np.ndarray:
          raise ValueError(
              "array_rs=" + str(array_rs) + "must be a numpy.ndarray")
  
      b_flux, c_flux = coef_rs
  
      array = (array_rs + c_flux) / b_flux
  
      return array