extract unique values from list of strings

Question

Hello, I have the following list of strings coming from a query: 
 
 List of Text String - 4 items "user1"(Text) "user2"(Text) "user2; user3"(Text) "user4"(Text) 
 
 How I can sort that so the final result will be list of strings of only unique values: 
 Result: "user1"(Text) "user2"(Text) "user3"(Text) "user4"(Text)

Peter Lewis · Accepted Answer

It looks like it's possible that there can be multiple values within a single text item - is that correct? Do you anticipate that it will always show with a semicolon separator if there are multiple values? 
 If you are confident in the format, you should be able to do this with several steps: (1) split each item by the semicolon (2) combine them all into a single list and (3) use the union() function to return a unique list of items. Something like this should work: 
 a!localVariables(
 local!data: {
 "user1",
 "user2",
 "user2; user3",
 "user4"
 },
 union(
 a!flatten(
 a!forEach(
 items: local!data,
 expression: trim(split(fv!item, ";"))
 )
 ),
 touniformstring({})
 )
)