Conditionally skip a branch of an expression tree in walks

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Strictly related to
JuliaSymbolics/TermInterface.jl#6

Let's say that I have
f . (A -> B) ⊗ g as an input expression and with a Postwalk I want to apply this set of rules:

g => g . (B -> C)
A => A . Ob(A)
B => B . Ob(B)
etc...

My goal is to apply all the rewrites only if the input expressions have not been tagged. Tagging means adding an outer expression with operation(ex) = (.) (dot, called a type tag). Therefore, I do not want to match and transverse on left . right expressions.
For example, f in the input expression IS tagged, while g IS NOT.
I do want to tag g and the outer \otimes, but I do not want to tag anything that is inside f . (A -> B).
See Metatheory.jl/test/category/test_cat.jl.

A simple solution would be not treating left . right expressions as trees in this context. But right after this task is done, i need to treat them like trees. Overriding the TermInterface.istree every time seems like an incorrect approach. Is conditional skipping of branches of expr. trees in Rewriters possible?

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cc @shashi