Convert a CSV SampleSheet to YAML run_info format.

def csv2yaml(in_file, out_file=None):
    """Convert a CSV SampleSheet to YAML run_info format.
    """
    if out_file is None:
        out_file = "%s.yaml" % os.path.splitext(in_file)[0]
    barcode_ids = _generate_barcode_ids(_read_input_csv(in_file))
    lanes = _organize_lanes(_read_input_csv(in_file), barcode_ids)
    with open(out_file, "w") as out_handle:
        out_handle.write(yaml.safe_dump(lanes, default_flow_style=False))
    return out_file