Define a class Board to play tic-tac-toe. 

Implement at least the behavior illustrated below:

  >>> 
  >>> b = Board()
  >>> b.show()
  - - -
  - - -
  - - -
  >>> b.whoseturn()
  Waiting for move from x
  >>> b.take(3, 6)
  Please specify your move correctly!
  >>> b.whoseturn()
  Waiting for move from x
  >>> b.take(1, 1)
  >>> b.show()
  - - -
  - x -
  - - -
  >>> b.whoseturn()
  Waiting for move from o
  >>> b.take(1, 1)
  Sorry, can't move there.
  >>> b.take(0, 1)
  >>> b.show()
  - o -
  - x -
  - - -
  >>> b.whoseturn()
  Waiting for move from x
  >>>