L_max parameter in Geometric Adstock class in PyMC Marketing

I am trying to build a MMM model using PyMC Marketing package. So I started with some default config like this:
sampler_config = {“progressbar”: True}

mmm = MMM(
model_config=model_config,
sampler_config=sampler_config,
date_column=date_column,
adstock=GeometricAdstock(l_max=10),
saturation=LogisticSaturation(),
channel_columns=channel_columns,
control_columns=control_columns,
yearly_seasonality=5,
)

Is there any way I can set different l_max values for different channels in this set up? I tried the following:
adstock_transforms = {
“Perf_Mktg_Visits”: GeometricAdstock(l_max=6), # longer carryover
“Travel_Ads_Visits’”: GeometricAdstock(l_max=4), # shorter carryover
“Perf_Mktg_Impressions”: GeometricAdstock(l_max=6), # medium carryover
“BED_Impressions”: GeometricAdstock(l_max=10),
“Social_Impressions”: GeometricAdstock(l_max=4),
“Affiliate_Clicks”: GeometricAdstock(l_max=4),
“Ecomm_Rev”: GeometricAdstock(l_max=6)
} and passed this dictionary inside the MMM class instance, but got an error. I guess it only accepts a Geometric Adstock class and not a dictionary. I am new to this, Would appreciate any help. If anyone has tried something along similar lines before?