text: import abc
  
  
  class Model(object):
      """ Represents an abstract base class """
      __metaclass__ = abc.ABCMeta
  
      def __init__(self, X_train, y_train, optimization_parameters={}):
          self.X_train = X_train
          self.y_train = y_train
          self.optimization_parameters = optimization_parameters
          self.model = None
  
      @abc.abstractmethod
      def train(self):
          pass
  
      @abc.abstractmethod
      def optimize(self):
          pass
  
      @abc.abstractmethod
      def predict(self):
          pass
  
      def score(self):
          if self.model is not None:
              return self.model.score(self.X_test, self.y_test)
  
      @abc.abstractmethod
      def save(self, filename):
          pass
  