Function flip

flip(
    board: Board,
    playerId: string,
    row: number,
    column: number,
): Promise<string>
Tries to flip over a card on the board, following the rules in the ps4 handout. If another player controls the card, then this operation waits until the flip either becomes possible or fails.
Parameters
- board: Board
  a Memory Scramble board
- playerId: string
  ID of player making the flip; must be a nonempty string of alphanumeric or underscore characters
- row: number
  row number of card to flip; must be an integer in [0, height of board), indexed from the top of the board
- column: number
  column number of card to flip; must be an integer in [0, width of board), indexed from the left of the board
Returns Promise<string>
the state of the board after the flip from the perspective of playerId, in the format described in the ps4 handout

Throws
an error (in a rejected promise) if the flip operation fails as described in the ps4 handout.