How to use the nbdev.__version__ function in nbdev

import psutil
    import torchvision
    try:
        import fastai2; fastver = fastai2.__version__
    except ImportError:
        fastver = 'fastai not found'
    try:
        import fastprogress; fastprog = fastprogress.__version__
    except ImportError:
        fastprog = 'fastprogress not found'
    try:
        import fastpages; fastp = fastpages.__version__
    except ImportError:
        fastp = 'fastpages not found'
    try:
        import nbdev; nbd = nbdev.__version__
    except ImportError:
        nbd = 'nbdev not found'

    print (BOLD +  RED + '>> Vision_UI Update: 03/17/2020')
    style = {'description_width': 'initial'}

    button = widgets.Button(description='System', button_style='success')
    ex_button = widgets.Button(description='Explore', button_style='success')
    display(button)

    out = widgets.Output()
    display(out)

    def on_button_clicked_info(b):
        with out:
            clear_output()