Probably I’m blind,

but is there a way to get the transformation

\frac{d}{d t} x(y(t)) = \frac{\partial x}{\partial y}(y(t)) \frac{\partial y}{\partial t}(t)

where x and y are symbolic. (I want do do a symbolic transformation on a PDE).

```
using Symbolics
@variables t x(..) y(..)
Dt = Differential(t)
e = Dt(x(y(t)))
expand_derivatives(e) # == Differential(t)(x(y(t)))
# is there some way to get something like
# magic( e ) == Differential(y)(x) * Differential(t)(x)
```

I understand that `x(..)`

implies that `x(y)`

stays unevaluated. So, the above code does what it should. But I cannot find a symbolic way to trigger the chain rule. (I’m open to use other packages)

(Maybe related: differentiation chain rule · Issue #157 · JuliaSymbolics/Symbolics.jl · GitHub )