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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 validate_unique(self, *args, **kwargs):
 """Checked whether more than one EighthSignup exists for a User on a given EighthBlock."""

        super(EighthSignup, self).validate_unique(*args, **kwargs)

        if self.has_conflict():
            raise ValidationError({NON_FIELD_ERRORS: ("EighthSignup already exists for the User and the EighthScheduledActivity's block",)})