             let startLine = file.line(for: token.offset, startFrom: 0)
             let endLine = file.line(for: token.offset + token.length, startFrom: startLine)
 
-            for lineNumber in startLine...endLine {
-                result.update(with: lineNumber)
-            }
+            result.formUnion(Set(startLine...endLine))
         }
         return result
     }

        return 0
    }
}

extension CharacterSet {
    var inverted: CharacterSet {
        var other = self

        other.invert()
        return other
    }
}

            "let a = 0\nvar x = 1\n\nx = 2\n",
            "a = 5\n\nvar x = 1\n",
            "struct X {\n\tvar a = 0\n}\n",
            "let a = 1 +\n\t2\nlet b = 5\n",
            "var x: Int {\n\treturn 0\n}\n"
        ],
        triggeringExamples: [
            "var x = 1\n↓x = 2\n",
            "a = 5\n↓var x = 1\n",
            "struct X {\n\tlet a\n\t↓func x() {}\n}\n",
            "var x: Int {\n\tlet a = 0\n\treturn a\n}\n"
        ]
    )

