Everyone knows the game "Tic-Tac-Toe". Your task is it, to evaluate an ascii tic-tac-toe matchfield. Your Programm/Function should output/return the winner: O, X or nobody (N).
X|O|X O|X|O O|O|X
In this case your programm/function should output/return 'X'
Input can come from STDIN, function arguments, command line argument, file, whatever suits you.
The program can be a function, full program, whatever works, really, as long as no external files are needed to run it.
You can assume that the input is valid.
X|O|X O|X|X = O O|O|O O|X|O X|X|O = X O|X|X X|O|X O|X|O = N O|X|O
This is code-colf, so the shortest answer (in bytes) wins.