<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _get_parser():
 """Parse input options."""

    import argparse

    parser = argparse.ArgumentParser(description=("Convert between mesh formats."))

    parser.add_argument("infile", type=str, help="mesh file to be read from")

    parser.add_argument(
        "--input-format",
        "-i",
        type=str,
        choices=input_filetypes,
        help="input file format",
        default=None,
    )

    parser.add_argument(
        "--output-format",
        "-o",
        type=str,
        choices=output_filetypes,
        help="output file format",
        default=None,
    )

    parser.add_argument("outfile", type=str, help="mesh file to be written to")

    parser.add_argument(
        "--prune",
        "-p",
        action="store_true",
        help="remove lower order cells, remove orphaned nodes",
    )

    parser.add_argument(
        "--prune-z-0",
        "-z",
        action="store_true",
        help="remove third (z) dimension if all points are 0",
    )

    parser.add_argument(
        "--version",
        "-v",
        action="version",
        version="%(prog)s {}, Python {}".format(__version__, sys.version),
        help="display version information",
    )

    return parser