For a multiplicative valuation, the interpretation turns `lawScale x` into multiplication by the scalar `v x`.

import Definitions.Def_TypeDensity_Basic
import Definitions.Def_TypeDensity_Formula_LawAlgebra
import Mathlib.FieldTheory.RatFunc.Basic
import Mathlib.MeasureTheory.Measure.Haar.Unique
import Mathlib.NumberTheory.ArithmeticFunction.Moebius
import Mathlib.NumberTheory.Padics.PadicIntegers
import Mathlib.RingTheory.IntegralClosure.IntegralRestrict
import Mathlib.RingTheory.MvPowerSeries.Basic
import Mathlib.RingTheory.RamificationInertia.Basic
import Mathlib.Topology.Algebra.Nonarchimedean.AdicTopology
import Mathlib.FieldTheory.Finite.GaloisField
import Mathlib.RingTheory.AdicCompletion.Algebra
import Mathlib.RingTheory.RegularLocalRing.Defs
set_option autoImplicit false

open TypeDensity
open scoped BigOperators ENNReal
variable {S : Type*} [Semiring S] (v : Expr → S)

theorem TypeDensity.lawInterp_lawScale (hv : ∀ x y, v (.mul x y) = v x * v y) (x : Expr) (L : Law) :
    lawInterp v (lawScale x L) = AddMonoidAlgebra.single 0 (v x) * lawInterp v L := by sorry