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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 save(self):
 """ Override the save method to save the first and last name to the user field. """

        # First save the parent form and get the user.
        new_user = super(SignupFormExtra, self).save()

        new_user.first_name = self.cleaned_data['first_name']
        new_user.last_name = self.cleaned_data['last_name']
        new_user.save()

        # Userena expects to get the new user from this form, so return the new
        # user.
        return new_user