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: xASL_adm_DeleteFileList.m
    path of file: ./repos/ExploreASL/External/SPMmodified/xASL
    
    the code of the file until where you have to start completion: function [filepaths, pathsNotDeleted] = xASL_adm_DeleteFileList(strDirectory, strRegEx, bRecurse, nRequired)
% Deletes files in the specified directory that match the regular expression.
%
% FORMAT: filepaths = xASL_adm_DeleteFileList(strDirectory, strRegEx[, bRecurse, nRequired])
%                     xASL_adm_DeleteFileList(strDirectory, strRegEx[, bRecurse, nRequired])
%
% INPUT:
%   strDirectory   Directory to search
%                  Optionally use wildcards to be more specific (i.e. 'C:\data\*.img')
%   strRegEx       Regular expression that will be used to filter the returned list.

    
function [filepaths, pathsNotDeleted] = xASL_adm_DeleteFileList(strDirectory, strRegEx, bRecurse, nRequired)
% Deletes files in the specified directory that match the regular expression.
%
% FORMAT: filepaths = xASL_adm_DeleteFileList(strDirectory, strRegEx[, bRecurse, nRequired])
%                     xASL_adm_DeleteFileList(strDirectory, strRegEx[, bRecurse, nRequired])
%
% INPUT:
%   strDirectory   Directory to search
%                  Optionally use wildcards to be more specific (i.e. 'C:\data\*.img')
%   strRegEx       Regular expression that will be used to filter the returned list.
%                  Examples: 
%                            '^.+$'       - matches all files (DEFAULT)
%                            '^\d+$'      - matches names that contains only digits
%                            '^.+\.nii$'  - matches names that end