Workflow Custom Function Working | Same Custom Function with Button

Workflow Custom Function Working | Same Custom Function with Button

Hi,

I have created a custom function to populate two Multi-Line fields with Character Limit: Small (2000 characters). 

The fields are called: "Inclusions" & "Exclusions"

After the workflow runs, the fields are:

Inclusions:
• Full export packing at residence
• Transport To Port
• South African Cargo Dues
• Export documentation and freight to destination
• Customs clearance at destination
• One delivery to residence
• Same day removal of debris
• Delivery to 1st floor
• Security trunk with exclusive container

Exclusions:
• Duties, taxes, demurrage or Other such disbursements
• Customs / Quarantine inspections fees
• Marine Insurance
• Storage and warehouse handling at destination
• Assembling of modular furniture
• Special arrangements if access at destination is difficult
• Split deliveries, abnormal access, lifts, hoists & parking fees
• Container cleaning fee
• Piano handling above 1st floor additional charges

I wanted to try achieve the same using a custom button however I notice when writing a custom function for a button it is different to writing a custom function for a workflow.

I have attached 3 images.

1. Custom Function for a Workflow
2. Creating the Button
3. Custom Function for a Button

Notice in 1. next to edit arguments it starts with void
Whilst in 2. next to edit arguments it starts with string

Why is there this difference? As a result the same script does not work. How can the code be changed to work with a Button?

As a final question;
In setting the variable for incl= 
I dont understand why it is adding the brackets i.e. "(((((((("
It doesn't do this to the excl=

Just in case the "\n" is confusing anyone, this is a line break.