Assertion failed
assert(null is String)
            |
            false

Assertion failed
assert(!(" is " is String))
       |        |
       |        true
       false

Assertion failed
assert(!(
       |
       false
    " is "

            is
            |
            true

            String
))

Assertion failed
assert(null/*is*/is/*is*/String)
                 |
                 false

Assertion failed
assert(!((null is String) is Boolean))
       |       |          |
       |       |          true
       |       false
       false