Command written by me:

1 mkdir -p mydir/{ colours/{primary/{pink,blue,inexperienced},blended/{yellow,orange,pink}},form/{circle,sq.,dice},animals/{mammals/{platypus,bat,canine},reptiles/{snakes,crocodile,lizard}}}
2 contact mydir/{colours,form,animals}

Output:

 common_script.sh  listing.sh 
 mydir  vpl_environment.sh  vpl_execution

    ./mydir:
    animals  colours  form

    ./mydir/animals:
    mammals  reptiles

    ./mydir/animals/mammals:
    bat  canine  platypus

    ./mydir/animals/mammals/bat:

    ./mydir/animals/mammals/canine:

    ./mydir/animals/mammals/platypus:

    ./mydir/animals/reptiles:
    crocodile  lizard  snakes

    ./mydir/animals/reptiles/crocodile:

    ./mydir/animals/reptiles/lizard:

    ./mydir/animals/reptiles/snakes:

    ./mydir/colours:
    primary  blended

    ./mydir/colours/primary:
    blue  inexperienced  pink

    ./mydir/colours/primary/blue:

    ./mydir/colours/primary/inexperienced:

    ./mydir/colours/primary/pink:

    ./mydir/colours/blended:
    orange  pink  yellow

    ./mydir/colours/blended/orange:

    ./mydir/colours/blended/pink:

    ./mydir/colours/blended/yellow:

    ./mydir/form:
    circle  dice  sq.

    ./mydir/form/circle:

    ./mydir/form/dice:

    ./mydir/form/sq.:

why i am getting these additional traces of output like:

    ./mydir/animals/mammals/bat:

    ./mydir/animals/mammals/canine:

    ./mydir/animals/mammals/platypus:


        ./mydir/animals/reptiles/crocodile:

        ./mydir/animals/reptiles/lizard:

        ./mydir/animals/reptiles/snakes:


        ./mydir/colours/primary/blue:

        ./mydir/colours/primary/inexperienced:

        ./mydir/colours/primary/pink:


        ./mydir/colours/blended/orange:

        ./mydir/colours/blended/pink:

        ./mydir/colours/blended/yellow:


        ./mydir/form/circle:

        ./mydir/form/dice:

        ./mydir/form/sq.: