Redshift Accepts IGNORE NULLS outside of expression

We've noticed placing INGORE NULLS inside and outside the expressions for FIRST_VALUE and LAST_VALUE yields the same semantic result. According to the docs it should be inside the expression. Is this expected behaviour or should Redshift only accept IGNORE NULLS inside the expression.

SELECT LAST_VALUE(venuename) IGNORE NULLS
    OVER (
        PARTITION BY venuestate
        ORDER BY venueseats
        ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    ) AS last_val
FROM venue

yields same result as

SELECT LAST_VALUE(venuename IGNORE NULLS)
    OVER (
        PARTITION BY venuestate
        ORDER BY venueseats
        ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    ) AS last_val
FROM venue