[Python] Polars group_by aggregating by sum is returning an error when using a dictionary

I'm trying to do a aggregation from a polars DataFrame. But I'm not getting what I'm expecting.

This is a minimal replication of the issue:

import polars as pl

# Create a DataFrame
df = pl.DataFrame({"category": ["A", "A", "B", "B", "B"],
"value": [1., 2., 3., 4., 5.]})

# Group by 'category' and sum 'value'
result = df.group_by("category").agg({"value": pl.sum})

# Print the result
print(result)



And I'm getting:

TypeError: specifying aggregations as a dictionary is not supported


but I'd like to get:

┌──────────┬─────────────────┐
│ category ┆ value │
│ --- ┆ --- │
│ str ┆ list[f64] │
╞══════════╪═════════════════╡
│ A ┆ 3.0 │
│ B ┆ 12.0 │
└──────────┴─────────────────┘



Any ideas on where the issue? thanks in advance.

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