import it
 
def getCatalog(name):
    ''' return a catalog by name, if not found
        then create a new one.
    '''
    model = it.app.GetModel()
    for cat in model.GetCatalogs():
        if cat.GetLabel() == name:
            return cat
    cat = it.app.NewCatalog(name)
    return cat

If you editing acmd.py heavily as you develop your code you might not want to keep quitting "it" to get it to reload acmd.py. We can't use python's reload() command because, for various reasons, acmd.py is not loaded as a python module. We can fix this by not loading acmd.py directly and instead using a intermediate loading script that does load import acmd.py as a module.