Shortest distance in binary maze

'''
we are using the grid as the visited array and when we push any point in queue,make it visted or in grid 0
'''
from typing import List
from collections import deque

def is_feasible(a,b,grid):
    if a>=0 and b>=0 and a<len(grid) and b<len(grid[0]) and grid[a][b]==1:
        return True
    return False

class Solution:
    def shortestPath(self,grid:List[List[int]],src: List[int], dest: List[int]) -> int:
        a,b=src[0],src[1]
        y,z=dest[0],dest[1]
        if grid[a][b]==0:
            return -1
        if src==dest:
            return 0

        q=deque()
        q.append([a,b,0])

        # mark source as visited directly in grid
        grid[a][b] = 0

        while len(q)>0:
            k=len(q)
            for i in range(k):
                a,b,dist=q.popleft()
                x_cord=[-1,0,1,0]
                y_cord=[0,1,0,-1]
                for k in range(4):
                    new_a=a+x_cord[k]
                    new_b=b+y_cord[k]
                    if new_a==y and new_b==z:
                        return dist+1

                    if is_feasible(new_a,new_b,grid):
                        q.append([new_a,new_b,dist+1])
                        # mark visited in grid
                        grid[new_a][new_b]=0
        return -1