== Why is this an issue?

``++!is++`` operator is used to check if an object is not of a specified type. While ``++ x !is Y++`` is an equivalent of ``++!(x is Y)++``, it is preferred to use the first one.
The ``++ x !is Y++`` syntax is more compact and more readable than the ``++!(x is Y)++`` syntax. Tt is also less error-prone when used in complex expressions.

=== Noncompliant code example

[source,dart]
----
if (!(x is Y)) {
  print("$x is not Y!")
}
----


=== Compliant solution

[source,dart]
----
if (x is! Y) {
  print("$x is not Y!")
}
----