typ = Tuple{Int,T} where T<:Real
unwtyp = Base.unwrap_unionall(typ) # Tuple{Int,T<:Real}
edited = edit(unwtyp,Real,Float64) # Tuple{Int,T<:Float64}, has free type variables.

I want to put Tuple{Int,T<:Float64} back to the form of Tuple{Int,T} where T<:Float64