As an aside, it’s fun to watch the function composition technique cause the called function get completely decomposed.
julia> f(x)=√(2x^2+1) > 5
f (generic function with 1 method)
julia> demo"f(_/2)"
>(_, 5) ∘ sqrt(_) ∘ +(_, 1) ∘ *(2, _) ∘ ^(_, 2) ∘ /(_, 2)
The constraint being, f cannot have any non-function operator (and for my demo, all functions called must be part of a function “whitelist”), and it cannot have x appear more than once.