Main: entry
Main: Calling procedure test1
    test1: entry
    test1: calling procedure subtest1
        subtest1: entry
        subtest1: exit subtest1
    test1: back from procedure subtest1
    test1: calling procedure subtest3
        subtest3: entry
        subtest3: exit subtest1
    test1: back from procedure subtest3
    test1: exit test1
Main: back from procedure test1
Main: Calling procedure test2
    test2: entry
    test2: calling procedure subtest2
        subtest2: entry
        subtest2: exit subtest1
    test2: back from procedure subtest2
    test2: calling procedure subtest1
        subtest1: entry
        subtest1: exit subtest1
    test2: back from procedure subtest1
    test2: exit test1
Main: back from procedure test2
Main: end main
