AWS Glue 3: NameError: name 'date_trunc' is not defined

Question

I built a job in AWS Glue Studio setting version to Glue 3, that is spark 3 is supported. Goal is to truncate the date in column "date" to the minute, that is all seconds set to 00.
I found function date_trunc to be used for that but I get error "NameError: name 'date_trunc' is not defined" The code runs in a custom transform and looks as follows:

def MyTransform (glueContext, dfc) -> DynamicFrameCollection:
    df = dfc.select(list(dfc.keys())[0]).toDF()
    df_rounded = df.withColumn("date_truncated", date_trunc("minute", col("date")))
    dyf_rounded = DynamicFrame.fromDF(df_rounded, glueContext, "rounded")
    return(DynamicFrameCollection({"CustomTransform0": dyf_rounded}, glueContext))

how can i make that function work? I assume I have to import that function but I dont see a way to do that in the Studio designer