I want a Function to return the nature of the first weekly candle of the month in Pine Script.

This code uses changes in the week of the year to determine the week of the month:

//@version=5
indicator("weekOfMonth()")
weekOfMonth(timestamp = time) =>
    var week = weekofyear(timestamp) %4
    if ta.change(weekofyear(timestamp))    
        week += 1
    if ta.change(month(timestamp))
        week := 1
    int result = timeframe.ismonthly ? na : week

plot(weekOfMonth())

How can I get the first weekly candle of the month in Pine Script?