1254. Number of Closed Islands

class Solution:
    def closedIsland(self, grid: List[List[int]]) -> int:
        
        def dfs(i,j, visited):
            if (i,j) in visited:
                return 
            if not self.isvalidland and (i == 0 or j == 0 or i == m-1 or j == n-1):
                self.isvalidland = True
            visited.add((i,j))
            
            for x,y in directions:
                if 0 <= i+x < m and 0 <= j+y < n and grid[i+x][j+y] == 0:
                    dfs( i+x, j+y, visited )
            
        
        if not grid:
            return 0
        m = len(grid)
        n = len(grid[0])
        count = 0
        visited = set()
        directions = [(0,1),(1,0),(0,-1),(-1,0)]
        for i in range(m):
            for j in range(n):
                self.isvalidland = False
                if (i,j) not in visited and grid[i][j] == 0:
                    dfs(i,j,visited)
                    count += 1 if(not self.isvalidland) else 0
        return count