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: mixGaussVb.m
    path of file: ./repos/PRMLT/chapter10
    
    the code of the file until where you have to start completion: function [label, model, L] = mixGaussVb(X, m, prior)
% Variational Bayesian inference for Gaussian mixture.
% Input: 

    
function [label, model, L] = mixGaussVb(X, m, prior)
% Variational Bayesian inference for Gaussian mixture.
% Input: 
%   X: d x n data matrix
%   m: k (1 x 1) or label (1 x n, 1<=label(i)<=k) or model structure
% Output:
%   label: 1 x n cluster label
%   model: trained model structure
%   L: variational lower bound
% Reference: Pattern Recognition and Machine Learning by Christopher M. Bishop (P.474)
% Written by Mo Chen (sth4nth@gmail.com).
fprintf('Variational Bayesian Gaussian mixture: running ... \n');
[d,n] = size(X);
if nargin < 3
    prior.alpha = 1;
    prior.kappa = 1;
    prior.m = mean(X,2);
    prior.v = d+1;
    prior.M = eye(d);   % M = inv(W)
end