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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 get_explorer_pid(self):
 """ Tries to find the process ID for "explorer.exe". @rtype: int or None @return: Returns the process ID, or C{None} on error. """

        try:
            exp = win32.SHGetFolderPath(win32.CSIDL_WINDOWS)
        except Exception:
            exp = None
        if not exp:
            exp = os.getenv('SystemRoot')
        if exp:
            exp = os.path.join(exp, 'explorer.exe')
            exp_list = self.find_processes_by_filename(exp)
            if exp_list:
                return exp_list[0][0].get_pid()
        return None