Function operator <<

extlibs/catch/include/catch/catch.hpp:7877–7880

    namespace {
        auto operator <<( std::ostream& os, ITransientExpression const& expr ) -> std::ostream& {
            expr.streamReconstructedExpression( os );
            return os;
        }
    }

    LazyExpression::LazyExpression( bool isNegated )