Implement a function to calculate the longest "snake" of ones that can be made from a starting position in a grid. A snake is made by moving right and down from a starting position as far as possible.

• Assumption: grid will be at least Ix', row and col will each be valid indexes in grid
• Restrictions: You may not use the max() or .in() functions.
• Examples: (cells is a 2D list below)
• Snake(cells,0,0) ? 1 # can't move in either direction
• Snake(cellS,0,2) ? 2 # can o down one, then no more moves
• Snake(cells,1,1) ? 5 # all he way down, and then right

1 0 1 0 0 1 1 1 1 1 0 1 0 0 1 1