How to pass on a parameter to a SSAS query

Does anyone know how to pass on a parameter to a SSAS query?

My current query is following

AnalysisServices.Database("powerbi://api.powerbi.com/v1.0/myorg/XYZ", "Budget", [Query="EVALUATE
VAR _1 = 2021
VAR _01 = 4
VAR _2 =
    FILTER (
        dx,
        dx[DataYear] = _1
            && dx[DataCAT] = "Forecast"
    )
............
........
", Implementation="2.0"])

I want to pass on a parameterized value to VAR _01 like following

let 
    var1=4,
    Source = AnalysisServices.Database("powerbi://api.powerbi.com/v1.0/myorg/XYZ", "Budget", [Query="EVALUATE
VAR _1 = 2021
VAR _01 = var1
VAR _2 =
    FILTER (
        dx,
        dx[DataYear] = _1
            && dx[DataCAT] = "Forecast"
    )
............
........
", Implementation="2.0"])
in 
  Source

Is it possible?

so far I have tried

let 
    var1=4,
    Source = AnalysisServices.Database("powerbi://api.powerbi.com/v1.0/myorg/XYZ", "Budget", [Query="EVALUATE
VAR _1 = 2021
VAR _01 = """&var1&"""
VAR _2 =
    FILTER (
        dx,
        dx[DataYear] = _1
            && dx[DataCAT] = "Forecast"
    )
............
........
", Implementation="2.0"])
in 
  Source

but it did not work.

Thank you in advance.