join function:

Join all the items in the list into a String. If list have non string items, it will return nuthing. If the second argument is omitted, the items will be separated by comma.

Examples:

• running: (join ["one", "two", "three"]) will give: "one, two, three"

• running: (join ["one", "two", "three"], " ; ") will give: "one ; two ; three"

• running: (join ["one", "two", 3]) will return nothing