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_vb_taylor_R.m
    path of file: ./repos/spm
    
    the code of the file until where you have to start completion: function [slice] = spm_vb_taylor_R(Y,slice)
% Get Taylor series approximation to posterior correlation matrices
% FORMAT [slice] = spm_vb_taylor_R(Y,slice)
%
% Y        - data
% slice    - VB-GLMAR data structure
%
% See paper VB3.
%__________________________________________________________________________

% Will Penny 
% Copyright (C) 2005-2022 Wellcome Centre for Human Neuroimaging


% Get mean hyperparameter values
h0 = [];
if slice.p > 0

    
function [slice] = spm_vb_taylor_R(Y,slice)
% Get Taylor series approximation to posterior correlation matrices
% FORMAT [slice] = spm_vb_taylor_R(Y,slice)
%
% Y        - data
% slice    - VB-GLMAR data structure
%
% See paper VB3.
%__________________________________________________________________________

% Will Penny 
% Copyright (C) 2005-2022 Wellcome Centre for Human Neuroimaging


% Get mean hyperparameter values
h0 = [];
if slice.p > 0
    if size(slice.ap_mean,2)==1
        % Single voxel in slice
        a      = slice.ap_mean';
        a_cov  = slice.a_cov{1};
    else
        a      = mean(slice.ap_mean');
        a_covs = cat(3,slice.a_cov{:});
        a_cov  = mean(a_covs,3);
    end