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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 addVariant(self,variant):
        '''Appends one Variant to variants

        '''
        if isinstance(variant, Variant):
            self.variants.append(variant)
        else:
            raise (VariantError,
                   'variant Type should be Variant, not %s' % type(variant))