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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def filelist_prune(self, at_data, *args, **kwargs):
 """ Given a list of files, possibly prune list by extension. """


        b_status    = True
        l_file      = []
        str_path    = at_data[0]
        al_file     = at_data[1]
        if len(self.str_extension):
            al_file = [x for x in al_file if self.str_extension in x]

        if len(al_file):
            al_file.sort()
            l_file      = al_file
            b_status    = True
        else:
            self.dp.qprint( "No valid files to analyze found in path %s!" % str_path, 
                            comms = 'error', level = 3)
            l_file      = None
            b_status    = False
        return {
            'status':   b_status,
            'l_file':   l_file
        }