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: likGumbel.m
    path of file: ./repos/bads/gpml-matlab-v3.6-2015-07-07/lik
    
    the code of the file until where you have to start completion: function [varargout] = likGumbel(sign, hyp, y, mu, s2, inf, i)

% likGumbel - Gumbel likelihood function for extremal value regression. 
% The expression for the likelihood is

    
function [varargout] = likGumbel(sign, hyp, y, mu, s2, inf, i)

% likGumbel - Gumbel likelihood function for extremal value regression. 
% The expression for the likelihood is
%   likGumbel(t) = exp(-z-exp(-z))/be, z = ga+s*(y-t)/be, be = sn*sqrt(6)/pi
% where s={+1,-1} is a sign switching between left and right skewed, ga is the
% Euler-Mascheroni constant, y is the mean, sn^2 is the variance.
% The skewness and kurtosis of likGumbel are 1.14*s and 2.4, respectively. 
%
% The hyperparameters are:
%
% hyp = [ log(sn)  ]
%
% Several modes are provided, for computing likelihoods, derivatives and moments
% respectively, see likFunctions.m for the details. In general, care is taken
% to avoid numerical issues when the arguments are extreme.
%
% Copyright (c) by Hannes Nickisch, 2013-11-01.
%
% See also LIKFUNCTIONS.M.

if nargin<4, varargout = {'1'}; return; end