docs: def add_custom_options(parser):
      """Adds custom options to a parser.
  
      :param parser: the parser to which to add options.
  
      :type parser: argparse.ArgumentParser
  
      """
      parser.add_argument("--report-title", type=str, metavar="TITLE",
                          default="Genetic Data Clean Up",
                          help="The report title. [default: %(default)s]")
      parser.add_argument("--report-author", type=str, metavar="AUTHOR",
                          default="pyGenClean",
                          help="The current project number. "
                               "[default: %(default)s]")
      parser.add_argument("--report-number", type=str, metavar="NUMBER",
                          default="Simple Project",
                          help="The current project author. "
                               "[default: %(default)s]")
      parser.add_argument("--report-background", type=str, metavar="BACKGROUND",
                          default="The aim of this project is to perform data "
                                  "QC prior to genetic analysis.",
                          help="Text of file containing the background section "
                               "of the report.")