The ... IsNot ... syntax is more compact and more readable than the Not ... Is ... syntax.

Noncompliant Code Example

Module Module1
    Sub Main()
        Dim a = Not "a" Is Nothing ' Noncompliant
    End Sub
End Module

Compliant Solution

Module Module1
    Sub Main()
        Dim a = "a" IsNot Nothing  ' Compliant
    End Sub
End Module