What factor does to unknown functions' arguments



factor( f(x-1/x) ) => f( (x^2-1)/x)

That is, factor calls sratsimp (with ratfac=T) on the arguments of unknown
functions, even though it doesn't actually factor them.

This seems peculiar.  Either it should map over all the arguments of f,
giving f((x-1)*(x+1)/x), or it should leave them completely untouched,
returning f(x-1/x).

Is there any disagreement about this?

             -s