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: DEMO_niche_construction.m
    path of file: ./repos/spm/toolbox/DEM
    
    the code of the file until where you have to start completion: function DEMO_niche_construction
% Demo of niche
    
function MDP = spm_maze_active(mdp,N,START,END)
% FORMAT MDP = spm_maze_search(mdp,N,START,END,alpha,beta,z)
% mdp   - MDP structure
% N     - number of moves (i.e., default 8)
% START - index of intial state (default 1)
% END   - index of target state (default 1)
% MDP   - MDP structure array

% preliminaries
%--------------------------------------------------------------------------
try, N;     catch, N     = 8;   end