[Python] How do I flatten the elements of a column of type list of lists so that it is a...

Consider the following example:

import polars as pl

pl.DataFrame(pl.Series("x", ["1, 0", "2,3", "5 4"])).with_columns(
pl.col("x").str.split(",").list.eval(pl.element().str.split(" "))
)


shape: (3, 1)
┌────────────────────┐
│ x │
│ --- │
│ list[list[str]] │
╞════════════════════╡
│ [["1"], ["", "0"]] │
│ [["2"], ["3"]] │
│ [["5", "4"]] │
└────────────────────┘


I want to flatten the elements of the column, so instead of being a nested list, the elements are just a list. How do I do that?

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