Combine two List variables in a single variable in custom script

Need to merge two lists into a single list, for example:

Using custom script
variable 1 = [1,2,3]
variable 2 = [4,5,6]
combinevariable = [1,2,3,4,5,6]

There is an example combining 2 lists in the KB: https://kb.workfusion.com/display/RPAe/Script+as+Custom+Action#ScriptasCustomAction-OperationswithRecorderVariables