public int at(int x, int y)
{
// The value must be zero or one.
int value_Renamed = matrix.get_Renamed(x, y);
if (!(value_Renamed == 0 || value_Renamed == 1))
{
// this is really like an assert... not sure what better exception to use?
throw new SystemException("Bad value");
}
return value_Renamed;
}