def add_histogram_args(parser):
    """Add arguments for specifying the histogram of wire lengths (i.e.
	cabinets/frames) available for a given system."""
    histogram_group = parser.add_argument_group('wire length histogram options'
        )
    histogram_mut_group = histogram_group.add_mutually_exclusive_group()
    histogram_mut_group.add_argument('--histogram-bins', '-H', type=int,
        metavar='N', default=5, help=
        'number of bins to pack wire lengths into in the histogram of wire lengths (default: %(default)s)'
        )
