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_estimate_PPI.m
    path of file: ./repos/bspm/thirdparty/gPPI_Toolbox/PPPIv13.1/PPPIv13
    
    the code of the file until where you have to start completion: function SPM=spm_estimate_PPI(Subject,SPM,Regions,Method,Analysis,Contrast,ConcatR,outdir,preservevarcorr,wb)
%Estimates 1st level PPI model
%   Subject is the subject number 
%   SPM is the 1st level activity model, used to pull values from

    
function SPM=spm_estimate_PPI(Subject,SPM,Regions,Method,Analysis,Contrast,ConcatR,outdir,preservevarcorr,wb)
%Estimates 1st level PPI model
%   Subject is the subject number 
%   SPM is the 1st level activity model, used to pull values from
%   Regions are the PPI seed regions
%   Method is 'cond' or 'trad'
%   Analysis is either 'psy', 'phy', or 'psyphy'
%   Contrast is a computational method variable:
%       0 not to estimate any contrasts;
%       1 to estimate contrasts;  
%       2 to only use PPI txt file for 1st level (not recommend