Function apply_binary

pub fn apply_binary<F>(
    a: Expr,
    b: Expr,
    f: F,
    output_type: SpecialEq<Arc<dyn FunctionOutputField>>,
) -> Expr
where
    F: 'static + Fn(Column, Column) -> Result<Option<Column>, PolarsError> + Send + Sync,

Like map_binary, but used in a group_by-aggregation context.

See Expr::apply for the difference between map and apply.