<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _clean_filepath(self, filepath):
 """ processes the filepath by checking if it is a directory or not and adding `.py` if not present. """

        if (os.path.isdir(filepath) and
                os.path.isfile(os.path.join(filepath, '__init__.py'))):

            filepath = os.path.join(filepath, '__init__.py')

        if (not filepath.endswith('.py') and
                os.path.isfile(filepath + '.py')):
            filepath += '.py'
        return filepath