Manage Order Management Extension groovy Scripting using IN/OR help required.

Summary:

Manage Order Management Extension groovy Scripting using IN/OR help required.

Content (please ensure you mask any confidential information):

I have the following groovy script coding:

if ( CategoryCode != "RETURN" && TransactionTypeCode == "SCCL_RMA_SO")
{header.setAttribute("TransactionTypeCode","SCCL_STOCKED");
}

if ( CategoryCode != "RETURN" && TransactionTypeCode == "SCCL_RMA")
{header.setAttribute("TransactionTypeCode","SCCL_STOCKED");
}

As you can see they are more or less the same with the exception of the TransactionTypeCode values.

How can i combine these lines into only one If Statement to check for both TransactionTypeCode values "SCCL_RMA_SO" and "SCCL_RMA"?

In SQL you would use an 'OR' or an 'IN' but how to i do the same in Groovy script?