shadows calculation

    def count_shadows(self, tree: Tree):
        cell: Cell = self.board[tree.cell_index]
        shadows = 0
        for day in range(6):
            distance = 0
            is_shadow = False
            c: Cell = self.board[tree.cell_index]
            while distance < 3:
                c: Cell = self.board[c.neighbors[day]]
                t: Tree = self.get_tree(c.cell_index)
                if t and t.cell_index >= 0 and t.size > distance and t.size >= tree.size:
                    is_shadow = True
                distance += 1
            if is_shadow: shadows += 1
        return shadows