def _call_function(function_name, arguments=None):
    """ Call given function and pass it in arguments if they are given.

    :param function_name: Function to call.
    :type function_name: str
    :param arguments:  Arguments object returned by ArgumentParser.parse_args()
    :type arguments: Namespace
    :return: None
    """
    function = globals().get(function_name)
    if arguments is None:
        function()
    else:
        function(arguments)
