I’m interested in computing the definite integral of some variable `X`

, defined in ModelingToolkit. For sake of example, consider something like:

```
X ~ Y * Z
D(Y) ~ Y * 2
D(Z) ~ Z / t
```

(in particular, `X`

is an “observed” in my case, AFAICT)

In the SciML world, these are the options?

- I can introduce
`D(integral_of_X) ~ X`

and let MTK deal with it. - I can use
`Integral(x in DomainSets.ClosedInterval(...))`

- Integrals.jl

I’m guessing that since it’s an observed, the fastest / most accurate is to set up an `IntegralProblem`

?