# Description
Write a function that accepts the current position of a knight in a chess board, it returns the possible positions that it will end up after 1 move. The resulted should be sorted. 
## Example
"a1" -> ["b3", "c2"]
def possible_positions(pos):
    board = [[r+str(c) for c in range(1,9)] for r in "abcdefgh"]
    x,y = ord(pos[0])-97,int(pos[1])-1
    return sorted([board[py][px] for py,px in 
              [(x+2,y+1),(x+2,y-1),(x-2,y+1),(x-2,y-1),(x+1,y+2),(x+1,y-2),(x-1,y+2),(x-1,y-2)]
        if 0 <= px < 8 and 0 <= py < 8])
def possible_positions(pos):
    board = [[r+str(c) for c in range(1,9)] for r in "abcdefgh"]
    x,y = ord(pos[0])-97,int(pos[1])-1
    return sorted([board[py][px] for py,px in 
              [(x+2,y+1),(x+2,y-1),(x-2,y+1),(x-2,y-1),(x+1,y+2),(x+1,y-2),(x-1,y+2),(x-1,y-2)]
        if 0 <= px < 8 and 0 <= py < 8])