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: palm_fliptree.m
    path of file: ./repos/CBIG/external_packages/matlab/non_default_packages/palm/palm-alpha109
    
    the code of the file until where you have to start completion: function Pset = palm_fliptree(Ptree,nP,cmc,idxout,maxP)
% Return a set of permutations from 
    
function palm_permtree.m, for easier readability.

% Get the number of possible sign-flips.
if nargin < 5,
    maxP = palm_maxshuf(Ptree,'flips');
    if nP > maxP,
        nP = maxP; % the cap is only imposed if maxP isn't supplied
    end