human
Solve the following python programming problem given the following code:
def __init__(self, sourcefiles, fileOptions, runSet, propertyfile = None, required_files_patterns = []) : 
    assert sourcefiles 
    self.identifier = sourcefiles [0] 
    self.sourcefiles = util.get_files (sourcefiles) 
    self.runSet = runSet 
    self.specific_options = fileOptions 
    self.log_file = ((runSet.log_folder + os.path.basename (self.identifier)) + '.log') 
    self.required_files = set () 
    rel_sourcefile = os.path.relpath (self.identifier, runSet.benchmark.base_dir) 
    for pattern in required_files_patterns : 
        this_required_files = runSet.expand_filename_pattern (pattern, runSet.benchmark.base_dir, rel_sourcefile) 
        if (not this_required_files) : 
            logging.warning ('Pattern %s in requiredfiles tag did not match any file for task %s.', pattern, self.identifier) 
self.required_files.update (this_required_files) 
self.required_files = list (self.required_files) 
    self.options = ((runSet.options + fileOptions) if fileOptions else runSet.options) 
    substitutedOptions = substitute_vars (self.options, runSet, self.identifier) 
    if (substitutedOptions != self.options) : 
        self.options = substitutedOptions 
self.propertyfile = (propertyfile or runSet.propertyfile) 
    def log_property_file_once(msg) : 
        if (not (self.propertyfile in _logged_missing_property_files)) : 
            _logged_missing_property_files.add (self.propertyfile) 
            logging.warning (msg) 
if (self.propertyfile is None) : 
        log_property_file_once ('No propertyfile specified. Results for C programs will be handled as UNKNOWN.') 
else : 
        expandedPropertyFiles = util.expand_filename_pattern (self.propertyfile, self.runSet.benchmark.base_dir) 
        substitutedPropertyfiles = substitute_vars ([self.propertyfile], runSet, self.identifier) 
        assert (len (<MASK>) == 1) 
        if expandedPropertyFiles : 
            if (len (expandedPropertyFiles) > 1) : 
                log_property_file_once ('Pattern {0} for sourcefile {1} in propertyfile tag...
    
    Given the code above, what is a proper replacement for <MASK>?
assistant
#Here is a proper replacement for <MASK>.
substitutedPropertyfiles