You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ValueFnIter_Case1_FHorz_TPath_SingleStep_fastOLG.m
    path of file: ./repos/VFIToolkit-matlab/TransitionPaths/FHorz/subcodes
    
    the code of the file until where you have to start completion: function [VKron, PolicyKron]=ValueFnIter_Case1_FHorz_TPath_SingleStep_fastOLG(VKron,n_d,n_a,n_z,N_j,d_grid, a_grid, z_gridvals_J, pi_z_J, ReturnFn, Parameters, DiscountFactorParamNames, ReturnFnParamNames, vfoptions)
% The VKron input is next period value fn, the VKron output is this period.
% 'fastOLG' just means parallelizing across all of the "ages" (j) at once.

% VKron=reshape(VKron,[prod(n_a),prod(n_z),N_j]);
PolicyKron=nan;

    
function [VKron, PolicyKron]=ValueFnIter_Case1_FHorz_TPath_SingleStep_fastOLG(VKron,n_d,n_a,n_z,N_j,d_grid, a_grid, z_gridvals_J, pi_z_J, ReturnFn, Parameters, DiscountFactorParamNames, ReturnFnParamNames, vfoptions)
% The VKron input is next period value fn, the VKron output is this period.
% 'fastOLG' just means parallelizing across all of the "ages" (j) at once.

% VKron=reshape(VKron,[prod(n_a),prod(n_z),N_j]);
PolicyKron=nan;

N_d=prod(n_d);
N_e=0;
if isfield(vfoptions,'n_e')
    N_e=prod(vfoptions.n_e);
end