def vararg_callback(option, opt_str, value, parser):
    """Callback for an option with variable arguments.
    Manually collect arguments right of a callback-action
    option (ie. with action="callback"), and add the resulting
    list to the destination var.

    Usage:
    parser.add_option("-c", "--callback", dest="vararg_attr",
                      action="callback", callback=vararg_callback)

    Details:
    http://docs.python.org/2/library/optparse.html#callback-example-6-variable
    -arguments
    """
    value = [value]

    def floatable(str):
        try:
            float(str)
            return True
        except ValueError:
            return False

    for arg in parser.rargs:
        # stop on --foo like options
        if arg[:2] == "--" and 2 > len(arg):
            break
        # stop on -a, but not on -3 or -3.0
        if arg[:1] == "-" and len(arg) > 1 and not floatable(arg):
            break
        value.append(arg)

    del parser.rargs[:len(value) - 1]
    setattr(parser.values, option.dest, value)


# The main entry point and bootstrapping.
dataset/ETHPy150Open beetbox/beets/beets/ui/__init__.py/vararg_callback/swapped operands of `>`