Hi!

I am trying to set up an ODE System similar to the very first example in ModelingToolkit. When I try to run e.g the code from the first example I get the error `UndefVarError: @named not defined’.

Anyone know what is going on? Here is the code

```
using ModelingToolkit
@variables t x(t) RHS(t) # independent and dependent variables
@parameters τ # parameters
D = Differential(t) # define an operator for the differentiation w.r.t. time
# your first ODE, consisting of a single equation, indicated by ~
@named fol_separate = ODESystem([ RHS ~ (1 - x)/τ,
D(x) ~ RHS ])
```