Behavior with shared lookup_name between AdstockTransformation and SaturationTransformation classes

[wd60622]

Example:

from pymc_marketing.mmm import AdstockTransformation, SaturationTransformation
from pymc_marketing.deserialize import deserialize

same_lookup_name = "identity"

def identity(x):
    return x

class NewAdstock(AdstockTransformation): 
    lookup_name = same_lookup_name
    function = identity
    default_priors = {}

# This is allowed but unreachable with the deserialize function
class NewSaturation(SaturationTransformation):
    lookup_name = same_lookup_name
    function = identity
    default_priors = {}

data = {"lookup_name": same_lookup_name, "l_max": 10}
instance = deserialize(data)

What is the expected behavior here?

1. Could be a call for a change in how they are serialized to make
   them more distinguishable.

NewAdstock().to_dict()
# {'lookup_name': 'identity',
#  'prefix': 'adstock',
#  'priors': {},
#  'l_max': 10,
#  'normalize': True,
#  'mode': 'After'}

NewSaturation().to_dict()
# {'lookup_name': 'identity',
#  'prefix': 'saturation',
#  'priors': {}}

2. Or cross-reference the lookup_name with the others to make it unique across all classes.

I am in favor of the first option