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: process_segment_fastsurfer.m
    path of file: ./repos/brainstorm3/toolbox/process/functions
    
    the code of the file until where you have to start completion: function varargout = process_segment_fastsurfer( varargin )
% PROCESS_SEGMENT_FASTSURFER: Run the segmentation o
    
function [isOk, errMsg] = Compute(iSubject, iAnatomy, nVertices, isInteractive, param, outdir)
    errMsg = '';
    isOk = 0;

    % ===== INSTALL FASTSURFER =====
    bst_progress('text', 'Testing FastSurfer installation...');
    % Get FreeSurfer path from environment variable
    FreeSurferDir = getenv('FREESURFER_HOME');
    SubjectsDir = getenv('SUBJECTS_DIR');
    if isempty(FreeSurferDir) || ~file_exist(FreeSurferDir) || isempty(SubjectsDir) || ~file_exist(SubjectsDir)
        errMsg = ['FreeSurfer is not installed on your computer.' 10 ...
                  'The environment variables FREESURFER_HOME and SUBJECTS_DIR must be set.' 10 10 ...
                  'See the online Brainstorm tutorial about FastSurfer for help:' 10 ...
                  'https://neuroimage.usc.edu/brainstorm/Tutorials/SegFastSurfer'];
        return
    end