how to get the max value of a column #359

Considering this line of code which in dataframes returns the max value of the "date" column, how can we do the same with diskframe? I tried multiple ways but none of them works.

max_date <- max(my.df$date,na.rm=TRUE)

this is the one that didn't work:

max <- (my.df %>% summarise(max(date, na.rm=T)))[[1]]

it returns an integer which is not a date obviously.