Checks the arguments and options.

def check_args(args):
    """Checks the arguments and options."""
    # Checking that only VCF can have a - (stdout) as output
    if args.output_format not in _streamable_format and args.output == "-":
        logger.error("{} format cannot be streamed to standard output"
                     "".format(args.output_format))
        sys.exit(1)

    # Checking the file extensions
    if args.output_format == "vcf" and args.output != "-":
        if not args.output.endswith(".vcf"):
            args.output += ".vcf"

    elif args.output_format == "plink":
        if args.output.endswith(".bed"):
            args.output = args.output[:-4]