Convert AppleScript date objects to UNIX timestamp or POSIX date format

unix_dates.scpt

-- convert an AppleScript Date object to a POSIX date CCYYMMDDHHmm.SS
on posixDate(datetime)
	-- date -j -f "%A, %B %e, %Y at %I:%M:%S %p" "Tuesday, September 1, 2015 at 11:00:00 AM" +%Y%m%d%H%M
	set command to "date -j -f '%A, %B %e, %Y at %I:%M:%S %p' '" & datetime & "'"
	set command to command & " +%Y%m%d%H%M.%S"
	
	set thePosixDate to do shell script command
	return thePosixDate
end posixDate

-- convert an AppleScript Date object to a UNIX timestamp (seconds since epoch)
on unixDate(datetime)
	set command to "date -j -f '%A, %B %e, %Y at %I:%M:%S %p' '" & datetime & "'"
	set command to command & " +%s"
	
	set theUnixDate to do shell script command
	return theUnixDate
end unixDate

Thanks.

How can we convert unix time to AppleScript date object?