Is there functionality similar to SymPy’s `collect`

in Symbolics.jl?

Alternatively I would appreciate another solution to this problem which maybe makes more sense:

I’m manipulating a multivariate symbolic equation in the Z-domain and want to pick off specific variables. This is what I’m looking at:

`(c*h + c*f*z + a*f*(z^2) + a*h*z - d*g - b*g*z - b*e*(z^2) - d*e*z) / (z^3)`

I’d like this simplified in terms of `z^(-n)`

rather than `z^(+n) / z^(+m)`

. Also, I want to reorganize the terms such that the symbolic coefficients are grouped by powers of `z`

. In SymPy this is done as `my_expr.expand().collect(z)`

. Is there a way to do this with Symbolics.jl?

Also, I want all symbolic coefficients of particular powers of `z`

; ideally I could have an iterator over all coefficients with the variable `z^(-1)`

and another iterator over all coefficients with variables not equal to `z^(-1)`