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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 clean(self):
 """ Always raise the default error message, because we don't care what they entered here. """

        raise forms.ValidationError(
            self.error_messages['invalid_login'],
            code='invalid_login',
            params={'username': self.username_field.verbose_name}
        )