Tango

Fill the grid so that each cell contains either a or a .
No more than 2 or may be next to each other, either vertically or horizontally.
Each row (and column) must contain the same number of and .
Cells separated by an = sign must be of the same type.
Cells separated by a X sign must be of the opposite type.
Each puzzle has one right answer and can be solved via deduction (you should never have to make a guess).