search.py

class Search(object):
    def __init__(self, state, *args, **kwargs):
        self.state = state
        self.cost_func = None

    def actions(self):
        """
        Returns a set of actions.
        """
        pass

    def transition(self, action):
        """
        Called on self.action(<choice>) and sets self.state
        to a new value.
        """
        pass

    def goal_test(self):
        """
        Checks self.state for the goal state.
        Returns a boolean.
        """
        raise Exception('self.goal_test has not been defined')

    def set_cost_func(self, func):
        """
        Sets the cost function.
        """
        self.cost_func = func