Consider having tagQuery()'s modifying methods return invisible()

[cpsievert]

I find it a little surprising this prints twice

x <- div(a(), span(), a())
xq <- tagQuery(x)
xq$addClass("foo")
xq

[cpsievert]

By hiding the result on modify, I think is a bit more clear that you're modifying xq

[schloerke]

I had originally approached it to be similar to plumber where the router should always be printed (never invisible).

But since it is not pipe methods, this seems fair.