[Python] group_by with polars concatenating values

I have a polars dataframe that I want to group by and concatenate the unique values in as a single entry.

in pandas, I go:

def unique_colun_values(x):
return('|'.join(set(x)))

dd=pd.DataFrame({'col1':[1,1,2,3,4],'col2':['a','a','a','b','b'],'col3':['qwe','rty','asd','fgh','zxc']})
dd.groupby('col1').agg(lambda x: unique_colun_values(x))


This works fine

when I try to implement in polars:

pl.from_pandas(dd).group_by('col1').agg(lambda x: unique_colun_values(x), allow_object=True)


I get the following error:

TypeError: cannot create expression literal for value of type function.

Hint: Pass `allow_object=True` to accept any value and create a literal of type Object.


Am I missing something?

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