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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 addVariantFeature(self,variantFeature):
        '''Appends one VariantFeature to variantFeatures
        '''
        if isinstance(variantFeature, Feature):
            self.features.append(variantFeature)
        else:
            raise(TypeError,
                  'variantFeature Type should be Feature, not %s' % type(
                    variantFeature)
                  )