Is it not allowed to call the B task in the A task in Gradle?

Help/Discuss
1 
task testHaHa {
    doFirst {
        if (true) {
            A()
//            tasks.named("A").get().execute()
        }else {
//            ...
        }
    }
}

task A {
    doFirst {
        println "A exec"
    }

}

I need to determine the A task, or other tasks when performing the TESTHAHA task according to the logic judgment, but I find that it cannot be implemented.
It always reports an error. How should I modify it?
I hope that A task is a task rather than a method, because the task seems to be more in line with Gradle’s design concept.

2

Yes, you are correct.
You cannot “call” one task from another task.
You can only model dependencies between tasks.