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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 model_to_objective(self, x_model):
        ''' This function serves as interface between model input vectors and
            objective input vectors
        '''
        idx_model = 0
        x_objective = []

        for idx_obj in range(self.objective_dimensionality):
            variable = self.space_expanded[idx_obj]
            new_entry = variable.model_to_objective(x_model, idx_model)
            x_objective += new_entry
            idx_model += variable.dimensionality_in_model

        return x_objective