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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 write(self, filename, header=None):
 """ Writes the AST as a configuration file. `filename` Filename to save configuration file to. `header` Header string to use for the file. Returns boolean. """


        origfile = self._filename

        try:
            with open(filename, 'w') as _file:
                self.writestream(_file, header)
                self._filename = filename
            return True

        except IOError:
            self._filename = origfile
            return False