code: def record_conflict(self, assignment, var, val, delta):
          "Record conflicts caused by addition or deletion of a Queen."
          n = len(self.vars)
          self.rows[val] += delta
          self.downs[var + val] += delta
          self.ups[var - val + n - 1] += deltf record_conflict(self, assignment, var, val, delta):
          "Record conflicts caused by addition or deletion of a Queen."
          n = len(self.vars)
          self.rows[val] += delta
          self.downs[var + val] += delta
          self.ups[var - val + n - 1] += delta
docs: Record conflicts caused by addition or deletion of a Queen.