class Square: def __init__(self, row, column, piece=None): self.row = row self.column = column self.piece = piece def has_piece(self): if self.piece is None: return False else: return True def is_rival(self, color): if self.has_piece() is True and self.piece.color != color: return True def empty_or_rival(self, color): if self.is_rival(color) is True or self.has_piece() is False: return True else: return False @staticmethod def on_board(*args): for arg in args: if arg < 0 or arg > 7: return False return True