number_place

Another rum of the mill trivial sudoku solver. Number Place was what it was called when it appeared in a Dell Magazine in 1979.
Example usage:
% python driver friday.csv
puzzle
_ 6 3 _ _ _ _ _ _
_ 4 _ _ 2 _ _ 7 _
8 _ _ _ 4 3 1 _ _
5 _ _ _ 6 7 _ _ _
_ _ 4 _ 1 _ 3 _ _
_ _ _ 9 5 _ _ _ 6
_ _ 9 1 7 _ _ _ 8
_ 1 _ _ 8 _ _ 9 _
_ _ _ _ _ _ 4 6 _
solution
2 6 3 7 9 1 8 4 5
9 4 1 5 2 8 6 7 3
8 7 5 6 4 3 1 2 9
5 8 2 3 6 7 9 1 4
6 9 4 8 1 2 3 5 7
1 3 7 9 5 4 2 8 6
4 2 9 1 7 6 5 3 8
3 1 6 4 8 5 7 9 2
7 5 8 2 3 9 4 6 1
%