> arround -> around [...]

Sorry for this mess.

> expr.as_leading_term(x,y) == expr.expand().as_leading_term(x,y)

Yes. But this doesn't give us a correct order term if the ``expr`` can be expanded.

For example: ``(x*(x+y)).as_leading_term(x,y)=x*y``.  But the correct O-term should be ``x**2+x*y`` (``if expr.is_Add`` branch).