def parse_arg(arg):
    """
    Parses arguments for convenience. Argument can be a
    csv list ('a,b,c'), a string, a list, a tuple.

    Returns a list.
    """
    # handle string input
    if type(arg) == str:
        arg = arg.strip()
        # parse csv as tickers and create children
        if ',' in arg:
            arg = arg.split(',')
            arg = [x.strip() for x in arg]
        # assume single string - create single item list
        else:
            arg = [arg]

    return arg