import pandas as pd
from sqlframe.duckdb import DuckDBSession

import narwhals as nw

session = DuckDBSession()
data = {"a": [1, 3, 4], "i": [0, 1, 2]}

df_pd = pd.DataFrame({"a": [1, 3, 4], "i": [0, 1, 2]})
sqlframe_df = session.createDataFrame(df_pd)
ldf = nw.from_native(sqlframe_df)

>>> ldf.with_columns(a_cum_sum=nw.col("a").cum_sum().over(order_by="i")).collect("pandas")
┌──────────────────┐
|Narwhals DataFrame|
|------------------|
|   a  i  a_cum_sum|
|0  1  0          1|
|1  3  1          4|
|2  4  2          8|
└──────────────────┘

import polars as pl

ldf = pl.LazyFrame(data)

>>> ldf.with_columns(a_cum_sum=pl.col("a").cum_sum().over(order_by="i")).collect()
TypeError: Expr.over() missing 1 required positional argument: 'partition_by'

>>> ldf.with_columns(a_cum_sum=pl.col("a").cum_sum().sort_by("i")).collect()
shape: (3, 3)
┌─────┬─────┬───────────┐
│ a   ┆ i   ┆ a_cum_sum │
│ --- ┆ --- ┆ ---       │
│ i64 ┆ i64 ┆ i64       │
╞═════╪═════╪═══════════╡
│ 1   ┆ 0   ┆ 1         │
│ 3   ┆ 1   ┆ 4         │
│ 4   ┆ 2   ┆ 8         │
└─────┴─────┴───────────┘