class FeatureVector():
    """
    Returns:
        the concept this feature vector represents
    """
    def get_concept(self):
        pass

    """
    Returns:
        the number of features in the feature vector
    """

    def get_num_features(self):
        pass

    """
    Args:
        i (int): the index of the feature in the vector

    Returns:
        the value of the feater with index i
    """

    def get_feature_value(self, i):
        pass
