cfnpp:
    parameters:
      MultiAz: True
      Param1: !var UseSecurity
    variables:
        UseSecurity: False
        UseMultiAz: False
        
Resources:
    MyResource:
        Name: A Resource
        AvailabilityZones: !if
            - MultiAz Param1 and
            -
              - us-east-1a
              - us-east-1b
            -
              - us-east-1a
        Test: !param Param1
        #Test2: !expr UseSecurity not