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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 bothify(self, text='## ??', letters=string.ascii_letters):
 """ Replaces all placeholders with random numbers and letters. :param text: string to be parsed :returns: string with all numerical and letter placeholders filled in """

        return self.lexify(self.numerify(text), letters=letters)