human
Solve the following python programming problem given the following code:
@ gen.engine 
def ProcessFiles(logs_store, merged_store, logs_paths, filenames, dry_run, callback) : 
    "Process each file contained in 'filenames'. Returns a list of successfully processed file names." 
    processed_files = [] 
    day_instance_logs = { 
        
} 
    s3_base = logs_paths.MergedDirectory () 
    @ gen.engine 
    def _AddEntry(instance, entry, callback) : 
        'Given a single log entry, validate it, find (or create) the corresponding LocalLogMerge and add it.' 
        if (not entry) : 
            callback () 
            return 
parsed = logs_util.ParseLogLine (entry) 
        if (not parsed) : 
            callback () 
            return 
(day, _, _, _) = parsed 
        day_log = None 
        if ((instance, day) not in day_instance_logs) : 
            day_instance_logs [(instance, day)] = log_merger.LocalLogMerge (merged_store, [day, instance], s3_base) 
            day_log = day_instance_logs [(instance, day)] 
            (yield gen.Task (day_log.FetchExistingFromS3)) 
day_log = day_instance_logs [(instance, day)] 
        day_log.Append (entry) 
        callback () 
@ gen.engine 
    def _ProcessOneFile(instance, contents, callback) : 
        'Iterate over a raw log file. Any line that does not start with a date in the form YYYY-MM-DD is considered
    part of a multi-line entry.
    TODO(marc): this will break horribly if we ever have multiple processes/threads logging to the same file.
    ' 
        buf = cStringIO.StringIO (contents) 
        buf.seek (0) 
        entry = '' 
        while True : 
            line = buf.readline () 
            if (not line) : 
                (yield gen.Task (_AddEntry, instance, entry)) 
                break 
if (line.startswith ((' ', '\t')) or (logs_util.ParseLogLine (line) is None)) : 
                entry += (' ' + line.strip ()) 
else : 
                (yield gen.Task (_AddEntry, instance, entry)) 
                entry = line.strip () 
buf.close () 
        callback () 
for filename in filenames : 
        instance =...

    
    

    Fix the buggy line: contents = (yield gen.Task (callback.Get, filename))
assistant
#Here is Python program to find (or create) the corresponding LocalLogMerge and add it.

contents = (yield gen.Task (logs_store.Get, filename))