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: HessianWrap.m
    path of file: ./repos/PESTO/private
    
    the code of the file until where you have to start completion: %% Hessian function for optimization
function Hessian = HessianWrap(negLogPost, varargin)
% This function is a dummy for the Hessian function from fm
    
function for optimization
function Hessian = HessianWrap(negLogPost, varargin)
% This function is a dummy for the Hessian function from fmincon
    
    if (nargin == 0)
        error('No parameter vector provided the Hessian function!');
    else
        theta = varargin{1}{1};
    end