python/exercises/queen-attack/example.py

class Queen(object):
    def __init__(self, row, column):
        if not 0 <= row <= 7 or not 0 <= column <= 7:
            raise ValueError("Invalid queen position: queen out of the board")
        self.row = row
        self.column = column

    def can_attack(self, another_queen):
        dx = abs(self.row - another_queen.row)
        dy = abs(self.column - another_queen.column)
        if dx == dy == 0:
            raise ValueError(
                'Invalid queen position: both queens in the same square')
        elif dx == dy or dx == 0 or dy == 0:
            return True
        else:
            return False