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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 blend(self, blend_recipe, join_base, join_blend):
 """Blend a recipe into the base recipe. This performs an inner join of the blend_recipe to the base recipe's SQL. """

        assert isinstance(blend_recipe, Recipe)

        self.blend_recipes.append(blend_recipe)
        self.blend_types.append('inner')
        self.blend_criteria.append((join_base, join_blend))
        self.dirty = True
        return self.recipe