class InPlaceStrategy():

    def get_delta_x(self):
        return 0

    def get_delta_y(self):
        return 0


class DiagonalStrategy():
    # bl, br, tl, tr
    # bottom left, bottom right, top left, top right
    directions = ["bl", "br", "tl", "tr"]

    # pass diagonally across screen
    def __init__(self, direction='tl'):
        self.direction = direction

    def get_delta_x(self):
        return 0

    def get_delta_y(self):
        return 0


class BlockStrategy():
    # move in tiny blocks down accross screen

    def get_delta_x(self):
        return 0

    def get_delta_y(self):
        return 10


class BossStrategy():
    # follow players and avoid bullets

    def get_delta_x(self):
        return 0

    def get_delta_y(self):
        return 0
