Miktotik scripting get/print bytes from specific rules

RouterOS Beginner Basics
1

How can i get or print current bytes value of specific rule - I tried something like this but i think it’s not working:

:local txbytes [/ip firewall mangle get [/ip firewall mangle find where chain=prerounting] bytes] ; :put $txbytes

Thank you!

2 
:local variable [/ip firewall mangle get number=1 bytes]
:log info $variable;

this gives you the value on rule number 1.
you can also use

find where

and use a condition to find a rule but make sure the result is only one rule, otherwise the logic breaks down here: you cannot assign mutiple values to a single variable.

also I use Terminal to workout the correct syntax . you can use Tab key to show the list of available commands or values to use