new_contents: """Provides parser for fastani subcommand."""
  
  from argparse import ArgumentDefaultsHelpFormatter, ArgumentParser, _SubParsersAction
  from pathlib import Path
  from typing import List, Optional
  
  from pyani import pyani_config
  from pyani.scripts import subcommands
  
  
  def build(
      subps: _SubParsersAction, parents: Optional[List[ArgumentParser]] = None
  ) -> None:
      """Return a command-line parser for the fastani subcommand.
  
      :param subps:  collection of subparsers in main parser
      :param parents:  parsers from which arguments are inherited
  
      The terminology may be confusing, but in practice the main parser collects
      command-line arguments that are then available to this parser, which inherits
      options from the parsers in `parents` in addition to those defined below.
      """
      parser = subps.add_parser(
          "anib", parents=parents, formatter_class=ArgumentDefaultsHelpFormatter
      )
      # Required positional arguments: input and output directories
      parser.add_argument(
          action="store",
          dest="indir",
          default=None,
          type=Path,
          help="input genome directory",
      )
      parser.add_argument(
          action="store",
          dest="outdir",
          default=None,
          type=Path,
          help="output analysis results directory",
      )
      # Optional arguments
      parser.add_argument(
          "--dbpath",
          action="store",
          dest="dbpath",
          default=Path(".pyani/pyanidb"),
          type=Path,
          help="path to pyani database",
      )
      parser.add_argument(
          "--fastani_exe",
          dest="fastani_exe",
          action="store",
          default=pyani_config.FASTANI_DEFAULT,
          type=Path,
          help="path to fastani executable",
      )
      '''parser.add_argument(
          "--format_exe",
          dest="format_exe",
          action="store",
          default=pyani_config.MAKEBLASTDB_DEFAULT,
          type=Path,
          help="path to makeblastdb executable",
      )
      parser.add_argument(
          "--fragsize",
          dest="fragsize",
          action="store",
          type=int,
          default=pyani_config.FRAGSIZE,
          help="blastn query fragment size",
      )'''
      parser.set_defaults(func=subcommands.subcmd_fastani)
  
subject: Create fastani_parser.py