Function concat_dataframes_with_axis_join 

pub fn concat_dataframes_with_axis_join(
    frames: &[&DataFrame],
    axis: i64,
    join: ConcatJoin,
) -> Result<DataFrame, FrameError>

Concatenate DataFrames along axis with explicit join policy.

Supported combinations:

• axis=0, join=outer|inner: row-wise concatenation
• axis=1, join=outer|inner: column-wise alignment