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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 filename(self, exists=os.path.exists, cython_suffix_re=CYTHON_SUFFIX_RE):
 """ A string with absolute path to file. :type: str """

        filename = self.frame.f_globals.get('__file__', '')
        if filename is None:
            filename = ''

        if filename.endswith(('.pyc', '.pyo')):
            filename = filename[:-1]
        elif filename.endswith('$py.class'):  # Jython
            filename = filename[:-9] + ".py"
        elif filename.endswith(('.so', '.pyd')):
            basename = cython_suffix_re.sub('', filename)
            for ext in ('.pyx', '.py'):
                cyfilename = basename + ext
                if exists(cyfilename):
                    filename = cyfilename
                    break
        return filename