Scenarios

Test A

concatenate {a} and {b} will result in {a}{b}
concatenate ddd and dd will result in ddddd
concatenate ddd and cc will result in dddcc

Test B

concatenate () and () will result in ()()

Test C

this test will also run with strange characters

concatenate bla and 〈〉 will result in bla〈〉

Test D

nullifying cdf and rising will give us 0.0F as output