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: spm_dcm_review.m
    path of file: ./repos/spm12
    
    the code of the file until where you have to start completion: function spm_dcm_review(DCM,action)
% Review an estimated DCM
% FORMAT spm_dcm_review(DCM,action)
%
% DCM    - DCM structure or its filename
% action - one of:
%          'fixed connections'
%          ['    effects of ' DCM.U.name{i}];
%          'contrast of connections'
%          'location of regions'
%          'inputs'
%          'outputs'
%          'kernels'

    
function spm_dcm_review(DCM,action)
% Review an estimated DCM
% FORMAT spm_dcm_review(DCM,action)
%
% DCM    - DCM structure or its filename
% action - one of:
%          'fixed connections'
%          ['    effects of ' DCM.U.name{i}];
%          'contrast of connections'
%          'location of regions'
%          'inputs'
%          'outputs'
%          'kernels'
%          'estimates of states'
%          'estimates of parameters'
%          'estimates of precisions'
%          ['   hidden states: ' DCM.Y.name{i}]
%__________________________________________________________________________
% Copyright (C) 2008-2018 Wellcome Trust Centre for Neuroimaging

% Karl Friston
% $Id: spm_dcm_review.m 7296 2018-04-18 10:36:49Z guillaume $


%-Get DCM structure
%==========================================================================
if ~nargin
    [DCM, sts] = spm_select(1,'^DCM.*\.mat$','select DCM_???.mat');
    if ~sts, return; end