def is_in_map(v)
      v.x >= 0 && v.y >= 0 && v.x < @size.x && v.y < @size.y
    end
def is_in_map(v)
      v.x >= 0 && v.y >= 0 && v.x < @size.x && v.y < @size.y
    end
Verifies whether a tile is inside the map.

 Parameters:
 [v] A Vector representing the tile, with x as the horizontal index and
     y as the vertical index.