final BooleanMatrix child = unaryExpr.expression().accept(this);
final ExprOperator op = unaryExpr.op();
switch(op) {
case TRANSPOSE : ret = child.transpose(); break;
case CLOSURE : ret = child.closure(); break;
case REFLEXIVE_CLOSURE : ret = child.closure().or(visit((ConstantExpression)Expression.IDEN)); break;
default :
throw new IllegalArgumentException("Unknown operator: " + op);
}