code: def addCustomOptions(parser):
      
      parser.add_argument("--format", type=str, metavar="FORMAT", default="png",
                          choices=["png", "ps", "pdf", "X11"],
                          help="The output file format (png, ps, pdf, or X11 "
                               "formats are available). [default: %(default)s]")
      parser.add_argument("--title", type=str, metavar="STRING",
                          default="C2 in function of C1 - MDS",
                          help="The title of the MDS plot. [default: "
                               "%(default)s]")
      parser.add_argument("--xlabel", type=str, metavar="STRING", default="C1",
                          help="The label of the X axis. [default: %(default)s]")
      parser.add_argument("--ylabel", type=str, metavar="STRING", default="C2",
                          help="The label of the Y axis. [default: %(default)s]")
docs: Adds custom options to a parser.
  
      :param parser: the parser.
  
      :type parser: argparse.parser